diff --git a/src/proto_alpha/lib_protocol/operation_repr.ml b/src/proto_alpha/lib_protocol/operation_repr.ml
index 7800df44295d1600d33d1bf73aeee9e2f6fc1f1a..5fcefe0170e9e7677360c34fed80bc7f57e3070a 100644
--- a/src/proto_alpha/lib_protocol/operation_repr.ml
+++ b/src/proto_alpha/lib_protocol/operation_repr.ml
@@ -1112,9 +1112,7 @@ module Encoding = struct
             obj3
               (req "rollup" Sc_rollup_repr.encoding)
               (req "opponent" Sc_rollup_repr.Staker.encoding)
-              (req
-                 "refutation"
-                 (option Sc_rollup_game_repr.refutation_encoding));
+              (opt "refutation" Sc_rollup_game_repr.refutation_encoding);
           select =
             (function
             | Manager (Sc_rollup_refute _ as op) -> Some op | _ -> None);
diff --git a/src/proto_alpha/lib_protocol/sc_rollup_errors.ml b/src/proto_alpha/lib_protocol/sc_rollup_errors.ml
index e5dc0c84f84bd1de44052d8cef892ada2ef78cdd..0e66e086f5368ef56c2a52d56c96bc8eb62792b4 100644
--- a/src/proto_alpha/lib_protocol/sc_rollup_errors.ml
+++ b/src/proto_alpha/lib_protocol/sc_rollup_errors.ml
@@ -256,11 +256,11 @@ let () =
     Data_encoding.empty
     (function Sc_rollup_not_staked_on_lcc -> Some () | _ -> None)
     (fun () -> Sc_rollup_not_staked_on_lcc) ;
-  let description = "Parent is not cemented." in
+  let description = "Parent is not the last cemented commitment." in
   register_error_kind
     `Temporary
     ~id:"Sc_rollup_parent_not_lcc"
-    ~title:"Parent not cemented"
+    ~title:"Parent is not the last cemented commitment"
     ~description
     ~pp:(fun ppf () -> Format.fprintf ppf "%s" description)
     Data_encoding.empty
diff --git a/src/proto_alpha/lib_protocol/sc_rollup_game_repr.ml b/src/proto_alpha/lib_protocol/sc_rollup_game_repr.ml
index 03b63228744c5cc61c426edffdf2b4cb969c5b91..6109671ffb0a83f4f19cbe16caa32ea2aa3fd4f7 100644
--- a/src/proto_alpha/lib_protocol/sc_rollup_game_repr.ml
+++ b/src/proto_alpha/lib_protocol/sc_rollup_game_repr.ml
@@ -109,7 +109,7 @@ module V1 = struct
          (fun {state_hash; tick} -> (state_hash, tick))
          (fun (state_hash, tick) -> {state_hash; tick})
          (obj2
-            (req "state" (option State_hash.encoding))
+            (opt "state" State_hash.encoding)
             (req "tick" Sc_rollup_tick_repr.encoding)))
 
   let encoding =
diff --git a/tezt/lib_tezos/client.ml b/tezt/lib_tezos/client.ml
index 7e5c355679473a7f0b99743a4173e95ea36c102f..b48b946ddc9f24ec9fac7cd1dbdd0d006a4ab1bf 100644
--- a/tezt/lib_tezos/client.ml
+++ b/tezt/lib_tezos/client.ml
@@ -1705,20 +1705,20 @@ module Sc_rollup = struct
     let parse process = Process.check process in
     {value = process; run = parse}
 
-  let spawn_cement_commitment ?hooks ?(wait = "none") ?burn_cap ~hash ~src ~dst
-      client =
-    spawn_command
-      ?hooks
-      client
-      (["--wait"; wait]
-      @ ["cement"; "commitment"; hash; "from"; src; "for"; "sc"; "rollup"; dst]
-      @ optional_arg "burn-cap" Tez.to_string burn_cap)
-
-  let cement_commitment ?hooks ?wait ?burn_cap ~hash ~src ~dst client =
+  let cement_commitment ?hooks ?(wait = "none") ?burn_cap ~hash ~src ~dst client
+      =
     let process =
-      spawn_cement_commitment ?hooks ?wait ?burn_cap ~hash ~src ~dst client
+      spawn_command
+        ?hooks
+        client
+        (["--wait"; wait]
+        @ [
+            "cement"; "commitment"; hash; "from"; src; "for"; "sc"; "rollup"; dst;
+          ]
+        @ optional_arg "burn-cap" Tez.to_string burn_cap)
     in
-    Process.check process
+    let parse process = Process.check process in
+    {value = process; run = parse}
 
   let submit_recover_bond ?(wait = "none") ?burn_cap ?storage_limit ?fee ?hooks
       ~rollup ~src client =
diff --git a/tezt/lib_tezos/client.mli b/tezt/lib_tezos/client.mli
index 298417903ac3b14104ab68b78b4ce9e57711b434..68267fa3fe00f96197ebc9a4bd786de00e15387a 100644
--- a/tezt/lib_tezos/client.mli
+++ b/tezt/lib_tezos/client.mli
@@ -1280,18 +1280,7 @@ module Sc_rollup : sig
     src:string ->
     dst:string ->
     t ->
-    unit Lwt.t
-
-  (** Same as [cement_commitment], but do not wait for the process to exit. *)
-  val spawn_cement_commitment :
-    ?hooks:Process.hooks ->
-    ?wait:string ->
-    ?burn_cap:Tez.t ->
-    hash:string ->
-    src:string ->
-    dst:string ->
-    t ->
-    Process.t
+    unit Runnable.process
 
   (** Run [tezos-client submit sc rollup recover bond to <sc_rollup> from <src>]. *)
   val submit_recover_bond :
diff --git a/tezt/tests/sc_rollup.ml b/tezt/tests/sc_rollup.ml
index 88eb31b37057135a1bc28525e051a74689e908a6..bc6531344dc9d858be26fe3557fe10f1e111335e 100644
--- a/tezt/tests/sc_rollup.ml
+++ b/tezt/tests/sc_rollup.ml
@@ -212,16 +212,17 @@ let first_published_at_level (_hash, (_ : Sc_rollup_client.commitment), level) =
 
 let predecessor (_hash, {Sc_rollup_client.predecessor; _}, _level) = predecessor
 
-let cement_commitment client ~sc_rollup ~hash =
-  let* () =
-    Client.Sc_rollup.cement_commitment
-      ~hooks
-      ~src:"bootstrap1"
-      ~dst:sc_rollup
-      ~hash
-      client
-  in
-  Client.bake_for_and_wait client
+let cement_commitment ?(src = "bootstrap1") ?fail ~sc_rollup ~hash client =
+  let p =
+    Client.Sc_rollup.cement_commitment ~hooks ~dst:sc_rollup ~src ~hash client
+  in
+  match fail with
+  | None ->
+      let*! () = p in
+      Client.bake_for_and_wait client
+  | Some failure ->
+      let*? process = p in
+      Process.check_error ~msg:(rex failure) process
 
 let publish_commitment ?(src = Constant.bootstrap1.public_key_hash) ~commitment
     client sc_rollup =
@@ -1906,16 +1907,16 @@ let test_rollup_client_list_keys =
           pp
           maybe_keys)
 
-let publish_dummy_commitment ~inbox_level ~predecessor ~sc_rollup ~src client =
+let publish_dummy_commitment ?(number_of_ticks = 1) ~inbox_level ~predecessor
+    ~sc_rollup ~src client =
   let commitment : Sc_rollup_client.commitment =
     {
       compressed_state = Constant.sc_rollup_compressed_state;
       inbox_level;
       predecessor;
-      number_of_ticks = 1;
+      number_of_ticks;
     }
   in
-
   let*! () = publish_commitment ~src ~commitment client sc_rollup in
   Client.bake_for_and_wait client