diff --git a/app/assets/javascripts/notes.js b/app/assets/javascripts/notes.js
index 042fe44e1c64176f4b9ff136695c9d756430ba41..877e873af7bdcf00257f8eaf3dd23d74dd6c8cf3 100644
--- a/app/assets/javascripts/notes.js
+++ b/app/assets/javascripts/notes.js
@@ -59,6 +59,7 @@ export default class Notes {
     this.postComment = this.postComment.bind(this);
     this.clearFlashWrapper = this.clearFlash.bind(this);
     this.onHashChange = this.onHashChange.bind(this);
+    this.handleQuickActionsCommands = this.handleQuickActionsCommands.bind(this);
 
     this.notes_url = notes_url;
     this.note_ids = note_ids;
@@ -292,16 +293,16 @@ export default class Notes {
 
   handleQuickActions(noteEntity) {
     var votesBlock;
-    if (noteEntity.commands_changes) {
-      if ('merge' in noteEntity.commands_changes) {
+    if (noteEntity.quick_actions_commands) {
+      if ('merge' in noteEntity.quick_actions_commands) {
         Notes.checkMergeRequestStatus();
       }
 
-      if ('emoji_award' in noteEntity.commands_changes) {
+      if ('emoji_award' in noteEntity.quick_actions_commands) {
         votesBlock = $('.js-awards-block').eq(0);
 
         loadAwardsHandler().then((awardsHandler) => {
-          awardsHandler.addAwardToEmojiBar(votesBlock, noteEntity.commands_changes.emoji_award);
+          awardsHandler.addAwardToEmojiBar(votesBlock, noteEntity.quick_actions_commands.emoji_award);
           awardsHandler.scrollToAwards();
         }).catch(() => {
           // ignore
@@ -338,6 +339,20 @@ export default class Notes {
     $note.toggleClass('target', addTargetClass);
   }
 
+  handleQuickActionsCommands(noteEntity, $notesList) {
+    const quickActionsCommands = noteEntity.quick_actions_commands;
+    const hasQuickActionsCommands = !_.isEmpty(quickActionsCommands);
+
+    if (hasQuickActionsCommands) {
+      $notesList.find('.system-note.being-posted').remove();
+      this.addFlash('Commands applied', 'notice', this.parentTimeline.get(0));
+
+      if (!noteEntity.valid) {
+        this.refresh();
+      }
+    }
+  }
+
   /**
    * Render note in main comments area.
    *
@@ -348,15 +363,9 @@ export default class Notes {
       return this.renderDiscussionNote(noteEntity, $form);
     }
 
+    this.handleQuickActionsCommands(noteEntity, $notesList);
+
     if (!noteEntity.valid) {
-      if (noteEntity.errors.commands_only) {
-        if (noteEntity.commands_changes &&
-            Object.keys(noteEntity.commands_changes).length > 0) {
-          $notesList.find('.system-note.being-posted').remove();
-        }
-        this.addFlash(noteEntity.errors.commands_only, 'notice', this.parentTimeline.get(0));
-        this.refresh();
-      }
       return;
     }
 
@@ -1549,7 +1558,7 @@ export default class Notes {
           this.reenableTargetFormSubmitButton(e);
         }
 
-        if (note.commands_changes) {
+        if (note.quick_actions_commands) {
           this.handleQuickActions(note);
         }
 
diff --git a/app/assets/javascripts/notes/components/comment_form.vue b/app/assets/javascripts/notes/components/comment_form.vue
index e594377bc4098dd4747b906c6f9e9d9e50e63093..3abccbce22fa7019afb882f5d3dfefbb1a2a6e87 100644
--- a/app/assets/javascripts/notes/components/comment_form.vue
+++ b/app/assets/javascripts/notes/components/comment_form.vue
@@ -139,15 +139,11 @@
               this.restartPolling();
 
               if (res.errors) {
-                if (res.errors.commands_only) {
-                  this.discard();
-                } else {
-                  Flash(
-                    'Something went wrong while adding your comment. Please try again.',
-                    'alert',
-                    this.$refs.commentForm,
-                  );
-                }
+                Flash(
+                  'Something went wrong while adding your comment. Please try again.',
+                  'alert',
+                  this.$refs.commentForm,
+                );
               } else {
                 this.discard();
               }
diff --git a/app/assets/javascripts/notes/stores/actions.js b/app/assets/javascripts/notes/stores/actions.js
index 085b18642baf4110e3521c2ca4147b1a3b2f818e..82278e76a669ddc2dec1baed672a83cbeb5c7b5e 100644
--- a/app/assets/javascripts/notes/stores/actions.js
+++ b/app/assets/javascripts/notes/stores/actions.js
@@ -61,6 +61,60 @@ export const createNewNote = ({ commit }, { endpoint, data }) => service
 export const removePlaceholderNotes = ({ commit }) =>
   commit(types.REMOVE_PLACEHOLDER_NOTES);
 
+const handleQuickActionsCommands = (noteEntity, noteData) => {
+  const quickActionsCommands = noteEntity.quick_actions_commands;
+  const hasQuickActionsCommands = !_.isEmpty(quickActionsCommands);
+  const quickActionsResults = noteEntity.quick_actions_results;
+  const hasQuickActionsResults = !_.isEmpty(quickActionsResults);
+  let quickActionsMessage = null;
+  let quickActionsMessageType = 'notice';
+
+  if (hasQuickActionsCommands || hasQuickActionsResults) {
+    quickActionsMessage = 'Commands applied';
+    eTagPoll.makeRequest();
+    $('.js-gfm-input').trigger('clear-commands-cache.atwho');
+
+    if (quickActionsCommands.emoji_award) {
+      const votesBlock = $('.js-awards-block').eq(0);
+
+      loadAwardsHandler()
+      .then((awardsHandler) => {
+        awardsHandler.addAwardToEmojiBar(votesBlock, quickActionsCommands.emoji_award);
+        awardsHandler.scrollToAwards();
+      })
+      .catch(() => {
+        Flash(
+          'Something went wrong while adding your award. Please try again.',
+          'alert',
+          noteData.flashContainer,
+        );
+      });
+    }
+
+    if (quickActionsCommands.spend_time != null
+      || quickActionsCommands.time_estimate != null) {
+      sidebarTimeTrackingEventHub.$emit('timeTrackingUpdated', noteEntity);
+    }
+  }
+
+  if (quickActionsResults && quickActionsResults.create_branch) {
+    const createBranchResult = quickActionsResults.create_branch;
+
+    if (createBranchResult.status === 'error') {
+      if (hasQuickActionsCommands) {
+        quickActionsMessage = quickActionsMessage.concat(`, but the branch '${createBranchResult.branch_name}' could not be created.`);
+      } else {
+        quickActionsMessage = `The branch '${createBranchResult.branch_name}' could not be created.`;
+        quickActionsMessageType = 'alert';
+      }
+    }
+  }
+
+  if (quickActionsMessage) {
+    Flash(quickActionsMessage, quickActionsMessageType, noteData.flashContainer);
+  }
+};
+
 export const saveNote = ({ commit, dispatch }, noteData) => {
   const { note } = noteData.data.note;
   let placeholderText = note;
@@ -92,42 +146,8 @@ export const saveNote = ({ commit, dispatch }, noteData) => {
 
   return dispatch(methodToDispatch, noteData)
     .then((res) => {
-      const { errors } = res;
-      const commandsChanges = res.commands_changes;
-
-      if (hasQuickActions && errors && Object.keys(errors).length) {
-        eTagPoll.makeRequest();
-
-        $('.js-gfm-input').trigger('clear-commands-cache.atwho');
-        Flash('Commands applied', 'notice', noteData.flashContainer);
-      }
+      handleQuickActionsCommands(res, noteData);
 
-      if (commandsChanges) {
-        if (commandsChanges.emoji_award) {
-          const votesBlock = $('.js-awards-block').eq(0);
-
-          loadAwardsHandler()
-            .then((awardsHandler) => {
-              awardsHandler.addAwardToEmojiBar(votesBlock, commandsChanges.emoji_award);
-              awardsHandler.scrollToAwards();
-            })
-            .catch(() => {
-              Flash(
-                'Something went wrong while adding your award. Please try again.',
-                'alert',
-                noteData.flashContainer,
-              );
-            });
-        }
-
-        if (commandsChanges.spend_time != null || commandsChanges.time_estimate != null) {
-          sidebarTimeTrackingEventHub.$emit('timeTrackingUpdated', res);
-        }
-      }
-
-      if (errors && errors.commands_only) {
-        Flash(errors.commands_only, 'notice', noteData.flashContainer);
-      }
       commit(types.REMOVE_PLACEHOLDER_NOTES);
 
       return res;
diff --git a/app/assets/javascripts/sidebar/components/time_tracking/sidebar_time_tracking.js b/app/assets/javascripts/sidebar/components/time_tracking/sidebar_time_tracking.js
index d32fe4abc7d036b4e7b6b903cbfd0e616f48cc6e..7ddbcff49fd7426d8ec0dde3edbd3244bacb99f5 100644
--- a/app/assets/javascripts/sidebar/components/time_tracking/sidebar_time_tracking.js
+++ b/app/assets/javascripts/sidebar/components/time_tracking/sidebar_time_tracking.js
@@ -29,8 +29,8 @@ export default {
       const subscribedCommands = ['spend_time', 'time_estimate'];
       let changedCommands;
       if (data !== undefined) {
-        changedCommands = data.commands_changes
-          ? Object.keys(data.commands_changes)
+        changedCommands = data.quick_actions_commands
+          ? Object.keys(data.quick_actions_commands)
           : [];
       } else {
         changedCommands = [];
diff --git a/app/controllers/concerns/notes_actions.rb b/app/controllers/concerns/notes_actions.rb
index e82a5650935301b99f0fb423c110ada6a390a426..2fd86a4ad23bc1f54ba1029f3e75dc155d2d6bbe 100644
--- a/app/controllers/concerns/notes_actions.rb
+++ b/app/controllers/concerns/notes_actions.rb
@@ -89,7 +89,8 @@ def note_html(note)
 
   def note_json(note)
     attrs = {
-      commands_changes: note.commands_changes
+      quick_actions_commands: note.quick_actions_commands,
+      quick_actions_results: note.quick_actions_results
     }
 
     if note.persisted?
diff --git a/app/controllers/projects/branches_controller.rb b/app/controllers/projects/branches_controller.rb
index 56df9991fdacdf796cfd600dcc368ad19b9b25cc..cffdf4c83937fade1d064efac27e3d4df680b335 100644
--- a/app/controllers/projects/branches_controller.rb
+++ b/app/controllers/projects/branches_controller.rb
@@ -38,18 +38,18 @@ def recent
   end
 
   def create
-    branch_name = sanitize(strip_tags(params[:branch_name]))
-    branch_name = Addressable::URI.unescape(branch_name)
-
     redirect_to_autodeploy = project.empty_repo? && project.deployment_platform.present?
-
-    result = CreateBranchService.new(project, current_user)
-        .execute(branch_name, ref)
-
-    if params[:issue_iid]
-      issue = IssuesFinder.new(current_user, project_id: @project.id).find_by(iid: params[:issue_iid])
-      SystemNoteService.new_issue_branch(issue, @project, current_user, branch_name) if issue
-    end
+    issue =
+      if params[:issue_iid]
+        IssuesFinder.new(current_user, project_id: project.id).find_by(iid: params[:issue_iid])
+      end
+    result =
+      if issue
+        Issues::CreateBranchService.new(project, current_user).execute(issue, params[:branch_name], ref)
+      else
+        ::CreateBranchService.new(project, current_user).execute(params[:branch_name], ref)
+      end
+    branch_name = result[:branch]&.name
 
     respond_to do |format|
       format.html do
@@ -58,7 +58,7 @@ def create
             redirect_to url_to_autodeploy_setup(project, branch_name),
               notice: view_context.autodeploy_flash_notice(branch_name)
           else
-            redirect_to project_tree_path(@project, branch_name)
+            redirect_to project_tree_path(project, branch_name)
           end
         else
           @error = result[:message]
diff --git a/app/controllers/projects/issues_controller.rb b/app/controllers/projects/issues_controller.rb
index 949eee51090ef86d2ce68dc722dc1111ce6fef4b..1f0431cecb2a71f01324585236ae25cb755db640 100644
--- a/app/controllers/projects/issues_controller.rb
+++ b/app/controllers/projects/issues_controller.rb
@@ -150,8 +150,7 @@ def related_branches
 
   def can_create_branch
     can_create = current_user &&
-      can?(current_user, :push_code, @project) &&
-      @issue.can_be_worked_on?(current_user)
+      Ability.can_create_branch_from_issue?(current_user, project, issuable)
 
     respond_to do |format|
       format.json do
diff --git a/app/models/ability.rb b/app/models/ability.rb
index 0b6bcbde5d94aa639a3a147d923d741eb2748eca..f4e6c8c45c658920c7b2be8a7639a64b994c0696 100644
--- a/app/models/ability.rb
+++ b/app/models/ability.rb
@@ -32,6 +32,11 @@ def can_edit_note?(user, note)
       allowed?(user, :edit_note, note)
     end
 
+    def can_create_branch_from_issue?(user, project, issue)
+      allowed?(user, :push_code, project) &&
+        issue.can_be_worked_on?(user)
+    end
+
     def allowed?(user, action, subject = :global, opts = {})
       if subject.is_a?(Hash)
         opts, subject = subject, :global
diff --git a/app/models/note.rb b/app/models/note.rb
index a42843037e90d617b2ff93bc2310d71c91fc6d1f..caa32f1102839b484e27e6e9cecfcb4b0d1fa08a 100644
--- a/app/models/note.rb
+++ b/app/models/note.rb
@@ -48,7 +48,9 @@ def values
   attr_accessor :user_visible_reference_count
 
   # Attribute used to store the attributes that have been changed by quick actions.
-  attr_accessor :commands_changes
+  attr_accessor :quick_actions_commands
+  # Attribute used to store results of quick actions that don't act on the note's noteable.
+  attr_accessor :quick_actions_results
 
   # A special role that may be displayed on issuable's discussions
   attr_accessor :special_role
diff --git a/app/services/create_branch_service.rb b/app/services/create_branch_service.rb
index 1f7e04e443562d1549a4920b5650a44dc1ab097d..9ab1fb46d49d8b6d6bc6602e37ffb3e012edab3b 100644
--- a/app/services/create_branch_service.rb
+++ b/app/services/create_branch_service.rb
@@ -1,29 +1,33 @@
 class CreateBranchService < BaseService
+  include ActionView::Helpers::SanitizeHelper
+
   def execute(branch_name, ref, create_master_if_empty: true)
     create_master_branch if create_master_if_empty && project.empty_repo?
 
+    sanitized_branch_name = sanitize_branch_name_for(branch_name)
+
     result = ValidateNewBranchService.new(project, current_user)
-      .execute(branch_name)
+      .execute(sanitized_branch_name)
 
     return result if result[:status] == :error
 
-    new_branch = repository.add_branch(current_user, branch_name, ref)
+    new_branch = repository.add_branch(current_user, sanitized_branch_name, ref)
 
     if new_branch
-      success(new_branch)
+      success(branch: new_branch)
     else
-      error('Invalid reference name')
+      error('Invalid reference name', nil, branch_name)
     end
   rescue Gitlab::Git::HooksService::PreReceiveError => ex
-    error(ex.message)
-  end
-
-  def success(branch)
-    super().merge(branch: branch)
+    error(ex.message,  nil, branch_name)
   end
 
   private
 
+  def error(message, http_status = nil, branch_name = nil)
+    super(message, http_status).merge(branch_name: branch_name)
+  end
+
   def create_master_branch
     project.repository.create_file(
       current_user,
@@ -33,4 +37,8 @@ def create_master_branch
       branch_name: 'master'
     )
   end
+
+  def sanitize_branch_name_for(branch_name)
+    Addressable::URI.unescape(sanitize(strip_tags(branch_name)))
+  end
 end
diff --git a/app/services/issues/create_branch_service.rb b/app/services/issues/create_branch_service.rb
new file mode 100644
index 0000000000000000000000000000000000000000..f5df44cd27250cbcf4203a86d9a8e68b41ea0002
--- /dev/null
+++ b/app/services/issues/create_branch_service.rb
@@ -0,0 +1,11 @@
+module Issues
+  class CreateBranchService < Issues::BaseService
+    def execute(issue, branch_name, ref)
+      ::CreateBranchService.new(project, current_user).execute(branch_name, ref).tap do |result|
+        if result[:status] == :success
+          SystemNoteService.new_issue_branch(issue, project, current_user, result[:branch].name)
+        end
+      end
+    end
+  end
+end
diff --git a/app/services/notes/create_service.rb b/app/services/notes/create_service.rb
index 9ea28733f5fe99aa9b4e07ccc7ebc8ae753a3226..179a08d1331e26f6356a13586d5769f249692d5a 100644
--- a/app/services/notes/create_service.rb
+++ b/app/services/notes/create_service.rb
@@ -19,9 +19,9 @@ def execute
 
       if quick_actions_service.supported?(note)
         options = { merge_request_diff_head_sha: merge_request_diff_head_sha }
-        content, command_params = quick_actions_service.extract_commands(note, options)
+        content, commands, results = quick_actions_service.extract_commands(note, options)
 
-        only_commands = content.empty?
+        only_quick_actions = content.empty? && (commands.any? || results.any?)
 
         note.note = content
       end
@@ -31,21 +31,14 @@ def execute
         NewNoteWorker.perform_async(note.id)
       end
 
-      if !only_commands && note.save
+      if !only_quick_actions && note.save
         todo_service.new_note(note, current_user)
       end
 
-      if command_params.present?
-        quick_actions_service.execute(command_params, note)
+      quick_actions_service.execute(commands, note)
 
-        # We must add the error after we call #save because errors are reset
-        # when #save is called
-        if only_commands
-          note.errors.add(:commands_only, 'Commands applied')
-        end
-
-        note.commands_changes = command_params
-      end
+      note.quick_actions_commands = commands
+      note.quick_actions_results = results
 
       note
     end
diff --git a/app/services/notes/quick_actions_service.rb b/app/services/notes/quick_actions_service.rb
index a8d0cc15527694c7cf3bc1b58b4a233e08a8d568..f15b40a6f340da33eba4fcbffc7546bb142a4e71 100644
--- a/app/services/notes/quick_actions_service.rb
+++ b/app/services/notes/quick_actions_service.rb
@@ -27,7 +27,7 @@ def extract_commands(note, options = {})
     end
 
     def execute(command_params, note)
-      return if command_params.empty?
+      return if command_params.blank?
       return unless supported?(note)
 
       self.class.noteable_update_service(note).new(project, current_user, command_params).execute(note.noteable)
diff --git a/app/services/quick_actions/interpret_service.rb b/app/services/quick_actions/interpret_service.rb
index 7332790b7b1219df747b463b4bb8f79b1c9cfe89..5bc3b07e5e9069ac595a37aacb856e8009abd1a9 100644
--- a/app/services/quick_actions/interpret_service.rb
+++ b/app/services/quick_actions/interpret_service.rb
@@ -15,11 +15,12 @@ def execute(content, issuable)
 
       @issuable = issuable
       @updates = {}
+      @results = {}
 
       content, commands = extractor.extract_commands(content, context)
       extract_updates(commands, context)
 
-      [content, @updates]
+      [content, @updates, @results]
     end
 
     # Takes a text and interprets the commands that are extracted from it.
@@ -451,7 +452,7 @@ def extractor
 
     desc 'Set target branch'
     explanation do |branch_name|
-      "Sets target branch to #{branch_name}."
+      "Sets target branch to `#{branch_name}`."
     end
     params '<Local branch name>'
     condition do
@@ -466,6 +467,23 @@ def extractor
       @updates[:target_branch] = branch_name if project.repository.branch_exists?(branch_name)
     end
 
+    desc 'Creates a new branch'
+    explanation do |branch_name = nil|
+      "Creates a `#{branch_name || issuable.to_branch_name}` branch."
+    end
+    params '<new-branch-name>'
+    condition do
+      issuable.is_a?(Issue) &&
+        issuable.persisted? &&
+        Ability.can_create_branch_from_issue?(current_user, project, issuable)
+    end
+    command :create_branch do |branch_name = nil|
+      branch_name ||= issuable.to_branch_name
+      ref = project.default_branch || 'master'
+      result = Issues::CreateBranchService.new(project, current_user).execute(issuable, branch_name, ref)
+      @results[:create_branch] = result
+    end
+
     desc 'Move issue from one column of the board to another'
     explanation do |target_list_name|
       label = find_label_references(target_list_name).first
diff --git a/app/services/validate_new_branch_service.rb b/app/services/validate_new_branch_service.rb
index 7d1ed768ee86f6abf1cfce94768d41b6fa99ba17..f67f9e1800ec43878369832ff7694d9465deafcd 100644
--- a/app/services/validate_new_branch_service.rb
+++ b/app/services/validate_new_branch_service.rb
@@ -5,15 +5,21 @@ def execute(branch_name)
     valid_branch = Gitlab::GitRefValidator.validate(branch_name)
 
     unless valid_branch
-      return error('Branch name is invalid')
+      return error('Branch name is invalid',  nil, branch_name)
     end
 
     if project.repository.branch_exists?(branch_name)
-      return error('Branch already exists')
+      return error('Branch already exists',  nil, branch_name)
     end
 
     success
   rescue Gitlab::Git::HooksService::PreReceiveError => ex
-    error(ex.message)
+    error(ex.message,  nil, branch_name)
+  end
+
+  private
+
+  def error(message, http_status = nil, branch_name = nil)
+    super(message, http_status).merge(branch_name: branch_name)
   end
 end
diff --git a/changelogs/unreleased/27801-new-branch-slash-command.yml b/changelogs/unreleased/27801-new-branch-slash-command.yml
new file mode 100644
index 0000000000000000000000000000000000000000..36af7bbe7ae19fde6c3029f58b97adf95cd985fa
--- /dev/null
+++ b/changelogs/unreleased/27801-new-branch-slash-command.yml
@@ -0,0 +1,4 @@
+---
+title: Add a new /create_branch slash command to create a branch from an issue.
+merge_request: 10384
+author: Nur Muhammad Bin Sirat
diff --git a/doc/user/project/quick_actions.md b/doc/user/project/quick_actions.md
index 6f729954bc8a0a071f4c766aa753772b4ea40c3c..b9c351126ea21e5a37fffdf89df5bd7f969f2cc0 100644
--- a/doc/user/project/quick_actions.md
+++ b/doc/user/project/quick_actions.md
@@ -15,9 +15,9 @@ do.
 | `/close`                   | Close the issue or merge request |
 | `/reopen`                  | Reopen the issue or merge request |
 | `/merge`                   | Merge (when pipeline succeeds) |
-| `/title <New title>`       | Change title |
-| `/assign @user1 @user2 `   | Add assignee(s) |
-| `/reassign @user1 @user2 ` | Change assignee(s) |
+| `/title New title`         | Change title |
+| `/assign @user1 @user2`    | Assign the issue or merge request to @user1 and @user2. You can also use `me` to assign the issue or merge request to yourself. |
+| `/reassign @user1 @user2`  | Assign the issue or merge request to @user1 and @user2. You can also use `me` to assign the issue or merge request to yourself. |
 | `/unassign @user1 @user2`  | Remove all or specific assignee(s) |
 | `/milestone %milestone`    | Set milestone |
 | `/remove_milestone`        | Remove milestone |
@@ -28,14 +28,15 @@ do.
 | `/done`                    | Mark todo as done |
 | `/subscribe`               | Subscribe |
 | `/unsubscribe`             | Unsubscribe |
-| <code>/due &lt;in 2 days &#124; this Friday &#124; December 31st&gt;</code> | Set due date |
-| `/remove_due_date`         | Remove due date |
+| <code>/due &lt;in 2 days &#124; this Friday &#124; December 31st&gt;</code> | Set a due date |
+| `/remove_due_date`         | Remove the due date |
 | `/wip`                     | Toggle the Work In Progress status |
 | <code>/estimate &lt;1w 3d 2h 14m&gt;</code> | Set time estimate |
 | `/remove_estimate`       | Remove estimated time |
 | <code>/spend &lt;time(1h 30m &#124; -1h 5m)&gt; &lt;date(YYYY-MM-DD)&gt;</code> | Add or subtract spent time; optionally, specify the date that time was spent on |
 | `/remove_time_spent`       | Remove time spent |
-| `/target_branch <Branch Name>` | Set target branch for current merge request |
+| `/target_branch branch-name` | Set target branch for the current merge request |
+| `/create_branch branch-name` | Create a new branch. If you don't pass a branch name, it automatically generates it based on the issue IID and title. |
 | `/award :emoji:`  | Toggle award for :emoji: |
 | `/weight <1-9>` | Set the weight of the issue |
 | `/clear_weight` | Clears the issue weight |
diff --git a/lib/gitlab/email/handler/create_note_handler.rb b/lib/gitlab/email/handler/create_note_handler.rb
index 8eea33b9ab512ce2202b4ecb0d90331d2b854c3c..5711bf2deca4738f83a51f7912a1e1f5996a7fbf 100644
--- a/lib/gitlab/email/handler/create_note_handler.rb
+++ b/lib/gitlab/email/handler/create_note_handler.rb
@@ -44,6 +44,16 @@ def sent_notification
         def create_note
           sent_notification.create_reply(message)
         end
+
+        def note_contains_only_quick_actions?(note)
+          note.note.empty? && (note.quick_actions_commands.any? || note.quick_actions_results.any?)
+        end
+
+        def verify_record!(record:, invalid_exception:, record_name:)
+          return if note_contains_only_quick_actions?(record)
+
+          super
+        end
       end
     end
   end
diff --git a/lib/gitlab/email/handler/reply_processing.rb b/lib/gitlab/email/handler/reply_processing.rb
index 32c5caf93e8118af01dbe3b41962b4301b4d910f..41f4dffb0fe506afdaf65d20850ca4023f000fc5 100644
--- a/lib/gitlab/email/handler/reply_processing.rb
+++ b/lib/gitlab/email/handler/reply_processing.rb
@@ -38,7 +38,6 @@ def validate_permission!(permission)
 
         def verify_record!(record:, invalid_exception:, record_name:)
           return if record.persisted?
-          return if record.errors.key?(:commands_only)
 
           error_title = "The #{record_name} could not be created for the following reasons:"
 
diff --git a/spec/controllers/projects/branches_controller_spec.rb b/spec/controllers/projects/branches_controller_spec.rb
index b22ec247cfd6ef30144189f29c0524a19514e268..08f6f2ea66d5f700528f7dd833034c38cc9bf9ec 100644
--- a/spec/controllers/projects/branches_controller_spec.rb
+++ b/spec/controllers/projects/branches_controller_spec.rb
@@ -101,8 +101,7 @@
         it 'redirects to newly created branch' do
           result = { status: :success, branch: double(name: branch) }
 
-          expect_any_instance_of(CreateBranchService).to receive(:execute).and_return(result)
-          expect(SystemNoteService).to receive(:new_issue_branch).and_return(true)
+          expect_any_instance_of(Issues::CreateBranchService).to receive(:execute).and_return(result)
 
           post :create,
             namespace_id: project.namespace.to_param,
@@ -152,8 +151,7 @@
 
           create(:cluster, :provided_by_gcp, projects: [project])
 
-          expect_any_instance_of(CreateBranchService).to receive(:execute).and_return(result)
-          expect(SystemNoteService).to receive(:new_issue_branch).and_return(true)
+          expect_any_instance_of(Issues::CreateBranchService).to receive(:execute).and_return(result)
 
           post :create,
             namespace_id: project.namespace.to_param,
diff --git a/spec/features/issues/user_uses_slash_commands_spec.rb b/spec/features/issues/user_uses_slash_commands_spec.rb
index b0babf005866e83fab9c60d0854a93312de04688..dea4880d7337deee3485d45610b85df9892ee7b1 100644
--- a/spec/features/issues/user_uses_slash_commands_spec.rb
+++ b/spec/features/issues/user_uses_slash_commands_spec.rb
@@ -340,5 +340,49 @@
         end
       end
     end
+
+    describe 'branch creation' do
+      let(:project) { create(:project, :public, :repository) }
+      let(:issue) { create(:issue, project: project) }
+
+      context 'when the user can create a branch' do
+        it 'creates the branch' do
+          write_note("/create_branch")
+
+          expect(page).not_to have_content '/create_branch'
+          expect(page).to have_content 'Commands applied'
+          expect(page).to have_content "created branch #{issue.to_branch_name}"
+        end
+      end
+
+      context 'when the user specifies an invalid branch name' do
+        it 'creates the branch' do
+          write_note("/create_branch A New Feature")
+
+          expect(page).not_to have_content '/create_branch'
+          expect(page).to have_content "The branch 'A New Feature' could not be created."
+        end
+      end
+
+      context 'when the user cannot create a branch' do
+        let(:guest) { create(:user) }
+
+        before do
+          project.add_guest(guest)
+          gitlab_sign_out
+          sign_in(guest)
+          visit project_issue_path(project, issue)
+        end
+
+        it 'does not create a branch' do
+          write_note("/create_branch")
+
+          expect(page).not_to have_content '/create_branch'
+          expect(page).not_to have_content 'Commands applied'
+
+          expect(project.repository.branch_names).not_to include(issue.to_branch_name)
+        end
+      end
+    end
   end
 end
diff --git a/spec/fixtures/emails/commands_only_reply.eml b/spec/fixtures/emails/only_quick_actions_reply.eml
similarity index 100%
rename from spec/fixtures/emails/commands_only_reply.eml
rename to spec/fixtures/emails/only_quick_actions_reply.eml
diff --git a/spec/fixtures/emails/commands_in_reply.eml b/spec/fixtures/emails/quick_actions_in_reply.eml
similarity index 100%
rename from spec/fixtures/emails/commands_in_reply.eml
rename to spec/fixtures/emails/quick_actions_in_reply.eml
diff --git a/spec/javascripts/notes_spec.js b/spec/javascripts/notes_spec.js
index e09b8dc7fc5450308419d945c0809cb721753fd8..22ffc0282585a709de4ad79a445a6cc1a6e67feb 100644
--- a/spec/javascripts/notes_spec.js
+++ b/spec/javascripts/notes_spec.js
@@ -550,16 +550,13 @@ import '~/notes';
       });
     });
 
-    describe('postComment with Slash commands', () => {
+    describe('postComment with Quick actions', () => {
       const sampleComment = '/assign @root\n/award :100:';
       const note = {
-        commands_changes: {
+        quick_actions_commands: {
           assignee_id: 1,
           emoji_award: '100'
         },
-        errors: {
-          commands_only: ['Commands applied']
-        },
         valid: false
       };
       let $form;
@@ -583,7 +580,7 @@ import '~/notes';
         $form.find('textarea.js-note-text').val(sampleComment);
       });
 
-      it('should remove slash command placeholder when comment with slash commands is done posting', () => {
+      it('should remove quick action placeholder when comment with quick actions is done posting', () => {
         const deferred = $.Deferred();
         spyOn($, 'ajax').and.returnValue(deferred.promise());
         spyOn(gl.awardsHandler, 'addAwardToEmojiBar').and.callThrough();
diff --git a/spec/lib/gitlab/email/handler/create_note_handler_spec.rb b/spec/lib/gitlab/email/handler/create_note_handler_spec.rb
index d0fa16ce4d17b3f407751f2a4c3213a582c2ce6b..b1f17adbd31551359f2ea8380b7aefd06557680f 100644
--- a/spec/lib/gitlab/email/handler/create_note_handler_spec.rb
+++ b/spec/lib/gitlab/email/handler/create_note_handler_spec.rb
@@ -56,7 +56,7 @@
     end
 
     context 'because the note was commands only' do
-      let!(:email_raw) { fixture_file("emails/commands_only_reply.eml") }
+      let!(:email_raw) { fixture_file("emails/only_quick_actions_reply.eml") }
 
       context 'and current user cannot update noteable' do
         it 'raises a CommandsOnlyNoteError' do
@@ -83,7 +83,7 @@
   end
 
   context 'when the note contains quick actions' do
-    let!(:email_raw) { fixture_file("emails/commands_in_reply.eml") }
+    let!(:email_raw) { fixture_file("emails/quick_actions_in_reply.eml") }
 
     context 'and current user cannot update noteable' do
       it 'post a note and does not update the noteable' do
diff --git a/spec/models/ability_spec.rb b/spec/models/ability_spec.rb
index 71aa51e185713182ca0943fefc682f30e72d0d72..ddc0342e3a208e8b5c1f98b29278f05138d95c64 100644
--- a/spec/models/ability_spec.rb
+++ b/spec/models/ability_spec.rb
@@ -267,4 +267,25 @@ def users_for_snippet(snippet)
       end
     end
   end
+
+  describe '.can_create_branch_from_issue?' do
+    let(:project) { create(:project) }
+    let(:issue) { create(:issue, project: project) }
+
+    context 'users with different access' do
+      it 'returns true for developer' do
+        developer = create(:user)
+        project.add_developer(developer)
+
+        expect(described_class.can_create_branch_from_issue?(developer, project, issue)).to eq(true)
+      end
+
+      it 'returns false for guest' do
+        guest = create(:user)
+        project.add_guest(guest)
+
+        expect(described_class.can_create_branch_from_issue?(guest, project, issue)).to eq(false)
+      end
+    end
+  end
 end
diff --git a/spec/services/issues/create_branch_service_spec.rb b/spec/services/issues/create_branch_service_spec.rb
new file mode 100644
index 0000000000000000000000000000000000000000..ae1f09b2cd8b0d4133492ed3e964c5bc020c983c
--- /dev/null
+++ b/spec/services/issues/create_branch_service_spec.rb
@@ -0,0 +1,27 @@
+require 'spec_helper'
+
+describe Issues::CreateBranchService, services: true do
+  let(:user) { create(:user) }
+  let(:service) { described_class.new(project, user) }
+
+  describe '#execute' do
+    context 'when repository is empty' do
+      let(:project) { create(:project, :repository) }
+      let(:issue) { create(:issue, project: project) }
+
+      it 'creates a branch if the branch name is valid and adds a system note' do
+        result = service.execute(issue, 'my-issue-branch', 'master')
+
+        expect(result[:status]).to eq(:success)
+        expect(issue.notes.last.note).to include('created branch [`my-issue-branch`]')
+      end
+
+      it 'does not create a branch if branch name is invalid' do
+        result = service.execute(issue, 'NOT valid name', 'master')
+
+        expect(result[:status]).to eq(:error)
+        expect(SystemNoteService).not_to receive(:new_issue_branch)
+      end
+    end
+  end
+end
diff --git a/spec/services/notes/create_service_spec.rb b/spec/services/notes/create_service_spec.rb
index 661d26946e79476bb4de6f0796230417d85ccd0a..5a2899724b2009490a899582150e9e6b0ab556b3 100644
--- a/spec/services/notes/create_service_spec.rb
+++ b/spec/services/notes/create_service_spec.rb
@@ -58,7 +58,7 @@
     end
 
     describe 'note with commands' do
-      describe '/close, /label, /assign & /milestone' do
+      describe '/close, /label & /assign' do
         let(:note_text) { %(HELLO\n/close\n/assign @#{user.username}\nWORLD) }
 
         it 'saves the note and does not alter the note text' do
diff --git a/spec/services/notes/quick_actions_service_spec.rb b/spec/services/notes/quick_actions_service_spec.rb
index 424cc9694d36f60dd60b0902abad63f56cb15361..d977181f262bbd40ad903b925a7c2e9a8877758d 100644
--- a/spec/services/notes/quick_actions_service_spec.rb
+++ b/spec/services/notes/quick_actions_service_spec.rb
@@ -23,10 +23,10 @@
         let(:note_text) { %(/close\n/assign @#{assignee.username}") }
 
         it 'saves the note and does not alter the note text' do
-          content, command_params = service.extract_commands(note)
+          content, commands, _results = service.extract_commands(note)
 
           expect(content).to eq note_text
-          expect(command_params).to be_empty
+          expect(commands).to be_empty
         end
       end
     end
@@ -36,10 +36,10 @@
         let(:note_text) { %(HELLO\n/close\n/assign @#{assignee.username}\nWORLD) }
 
         it 'saves the note and does not alter the note text' do
-          content, command_params = service.extract_commands(note)
+          content, commands, _results = service.extract_commands(note)
 
           expect(content).to eq note_text
-          expect(command_params).to be_empty
+          expect(commands).to be_empty
         end
       end
     end
@@ -62,8 +62,8 @@
         end
 
         it 'closes noteable, sets labels, assigns, and sets milestone to noteable, and leave no note' do
-          content, command_params = service.extract_commands(note)
-          service.execute(command_params, note)
+          content, commands, _results = service.extract_commands(note)
+          service.execute(commands, note)
 
           expect(content).to eq ''
           expect(note.noteable).to be_closed
@@ -81,8 +81,8 @@
         let(:note_text) { '/reopen' }
 
         it 'opens the noteable, and leave no note' do
-          content, command_params = service.extract_commands(note)
-          service.execute(command_params, note)
+          content, commands, _results = service.extract_commands(note)
+          service.execute(commands, note)
 
           expect(content).to eq ''
           expect(note.noteable).to be_open
@@ -93,8 +93,8 @@
         let(:note_text) { '/spend 1h' }
 
         it 'updates the spent time on the noteable' do
-          content, command_params = service.extract_commands(note)
-          service.execute(command_params, note)
+          content, commands, _results = service.extract_commands(note)
+          service.execute(commands, note)
 
           expect(content).to eq ''
           expect(note.noteable.time_spent).to eq(3600)
@@ -109,8 +109,8 @@
         end
 
         it 'closes noteable, sets labels, assigns, and sets milestone to noteable' do
-          content, command_params = service.extract_commands(note)
-          service.execute(command_params, note)
+          content, commands, _results = service.extract_commands(note)
+          service.execute(commands, note)
 
           expect(content).to eq "HELLO\nWORLD"
           expect(note.noteable).to be_closed
@@ -128,8 +128,8 @@
         let(:note_text) { "HELLO\n/reopen\nWORLD" }
 
         it 'opens the noteable' do
-          content, command_params = service.extract_commands(note)
-          service.execute(command_params, note)
+          content, commands, _results = service.extract_commands(note)
+          service.execute(commands, note)
 
           expect(content).to eq "HELLO\nWORLD"
           expect(note.noteable).to be_open
@@ -242,8 +242,8 @@
       end
 
       it 'adds only one assignee from the list' do
-        _, command_params = service.extract_commands(note)
-        service.execute(command_params, note)
+        _content, commands, _results = service.extract_commands(note)
+        service.execute(commands, note)
 
         expect(note.noteable.assignees.count).to eq(2)
       end
diff --git a/spec/services/quick_actions/interpret_service_spec.rb b/spec/services/quick_actions/interpret_service_spec.rb
index f54cb1f965bbc4c17ca0e5aa692073d11de4c130..d1591c2239d2fb50874d675b371f18884aef6452 100644
--- a/spec/services/quick_actions/interpret_service_spec.rb
+++ b/spec/services/quick_actions/interpret_service_spec.rb
@@ -341,6 +341,36 @@
       end
     end
 
+    shared_examples 'create branch command' do
+      context 'without params' do
+        it 'creates a new branch with issue title as branch name' do
+          _content, updates, results = service.execute('/create_branch', issuable)
+
+          expect(project.repository.branch_names).to include(issuable.to_branch_name)
+          expect(updates).to be_empty
+          expect(results[:create_branch]).to include({ status: :success })
+        end
+      end
+
+      context 'with params' do
+        it 'creates a new branch if the params is a valid branch name' do
+          _content, updates, results = service.execute("/create_branch #{valid_branch_name}", issuable)
+
+          expect(project.repository.branch_names).to include(valid_branch_name)
+          expect(updates).to be_empty
+          expect(results[:create_branch]).to include({ status: :success })
+        end
+
+        it 'does not create a new branch if the params is an invalid branch name' do
+          _content, updates, results = service.execute("/create_branch #{invalid_branch_name}", issuable)
+
+          expect(project.repository.branch_names).not_to include(invalid_branch_name)
+          expect(updates).to be_empty
+          expect(results[:create_branch]).to include({ status: :error })
+        end
+      end
+    end
+
     it_behaves_like 'reopen command' do
       let(:content) { '/reopen' }
       let(:issuable) { issue }
@@ -995,6 +1025,35 @@
       end
     end
 
+    context '/create_branch command' do
+      let(:project) { create(:project, :repository) }
+      let(:service) { described_class.new(project, developer) }
+      let(:issue) { create(:issue, title: 'Some Big Issue', project: project) }
+      let(:valid_branch_name) { 'valid/branch-Name' }
+
+      it_behaves_like 'create branch command' do
+        let(:issuable) { issue }
+        let(:invalid_branch_name) { 'Invalid Name For A Branch' }
+      end
+
+      context 'unprivileged user' do
+        let(:other_user) { create(:user) }
+        let(:service) { described_class.new(project, other_user)}
+
+        it_behaves_like 'empty command' do
+          let(:content) { "/create_branch #{valid_branch_name}" }
+          let(:issuable) { issue }
+        end
+      end
+
+      context 'on merge requests' do
+        it_behaves_like 'empty command' do
+          let(:content) { "/create_branch #{valid_branch_name}" }
+          let(:issuable) { create(:merge_request, source_project: project) }
+        end
+      end
+    end
+
     context '/board_move command' do
       let(:todo) { create(:label, project: project, title: 'To Do') }
       let(:inreview) { create(:label, project: project, title: 'In Review') }
@@ -1255,12 +1314,36 @@
     end
 
     describe 'target branch command' do
-      let(:content) { '/target_branch my-feature ' }
+      let(:content) { '/target_branch my-feature' }
 
       it 'includes the branch name' do
         _, explanations = service.explain(content, merge_request)
 
-        expect(explanations).to eq(['Sets target branch to my-feature.'])
+        expect(explanations).to eq(['Sets target branch to `my-feature`.'])
+      end
+    end
+
+    describe 'create branch command' do
+      let(:project) { create(:project, :repository, :public) }
+
+      context 'without a branch name' do
+        let(:content) { '/create_branch' }
+
+        it 'includes the branch name' do
+          _, explanations = service.explain(content, issue)
+
+          expect(explanations).to eq(["Creates a `#{issue.to_branch_name}` branch."])
+        end
+      end
+
+      context 'with a branch name' do
+        let(:content) { '/create_branch my-branch' }
+
+        it 'includes the branch name' do
+          _, explanations = service.explain(content, issue)
+
+          expect(explanations).to eq(["Creates a `my-branch` branch."])
+        end
       end
     end