diff --git a/src/lib_protocol_environment/environment_V8.ml b/src/lib_protocol_environment/environment_V8.ml
index 87cf7962e1dc7a18275dc1295d1adc37aa6adc6e..d99e65dc5a575fb7febe95631ada2700417d1ac8 100644
--- a/src/lib_protocol_environment/environment_V8.ml
+++ b/src/lib_protocol_environment/environment_V8.ml
@@ -1137,6 +1137,8 @@ struct
 
         let wrap t = PVM_tree t
       end)
+
+      let initial_state = initial_state V0
     end
   end
 
diff --git a/src/lib_protocol_environment/environment_V9.ml b/src/lib_protocol_environment/environment_V9.ml
index 78bc7a788f00a9257b6dcd42b15e5f66d93dcf7e..a4af1d5887981c9909724eedffa3c338030e0562 100644
--- a/src/lib_protocol_environment/environment_V9.ml
+++ b/src/lib_protocol_environment/environment_V9.ml
@@ -114,6 +114,7 @@ module type T = sig
        and type Dal.page_proof = Tezos_crypto_dal.Cryptobox.Verifier.page_proof
        and type Bounded.Non_negative_int32.t =
         Tezos_base.Bounded.Non_negative_int32.t
+       and type Wasm_2_0_0.version = Tezos_scoru_wasm.Wasm_pvm_state.version
        and type Wasm_2_0_0.input = Tezos_scoru_wasm.Wasm_pvm_state.input_info
        and type Wasm_2_0_0.output = Tezos_scoru_wasm.Wasm_pvm_state.output_info
        and type Wasm_2_0_0.reveal_hash =
@@ -1126,6 +1127,10 @@ struct
       input_request : input_request;
     }
 
+    type version = Tezos_scoru_wasm.Wasm_pvm_state.version
+
+    let v0 = Tezos_scoru_wasm.Wasm_pvm_state.V0
+
     module Make
         (Tree : Context.TREE with type key = string list and type value = bytes) =
     struct
diff --git a/src/lib_protocol_environment/environment_V9.mli b/src/lib_protocol_environment/environment_V9.mli
index 6426410d4b4dc895e5e05d8bceff22de309c5e02..4213335f5bc111aa7cd9aa2733b3e412d7cb84f6 100644
--- a/src/lib_protocol_environment/environment_V9.mli
+++ b/src/lib_protocol_environment/environment_V9.mli
@@ -114,6 +114,7 @@ module type T = sig
        and type Dal.page_proof = Tezos_crypto_dal.Cryptobox.Verifier.page_proof
        and type Bounded.Non_negative_int32.t =
         Tezos_base.Bounded.Non_negative_int32.t
+       and type Wasm_2_0_0.version = Tezos_scoru_wasm.Wasm_pvm_state.version
        and type Wasm_2_0_0.input = Tezos_scoru_wasm.Wasm_pvm_state.input_info
        and type Wasm_2_0_0.output = Tezos_scoru_wasm.Wasm_pvm_state.output_info
        and type Wasm_2_0_0.reveal_hash =
diff --git a/src/lib_protocol_environment/sigs/v9.ml b/src/lib_protocol_environment/sigs/v9.ml
index 1339a6194915e9aaf16df6f25b577337942bc0df..4694f64a1daa8cc91629cccf51b00d8619ee72ec 100644
--- a/src/lib_protocol_environment/sigs/v9.ml
+++ b/src/lib_protocol_environment/sigs/v9.ml
@@ -12078,6 +12078,10 @@ end
 (*                                                                           *)
 (*****************************************************************************)
 
+type version
+
+val v0 : version
+
 type input = {inbox_level : Bounded.Non_negative_int32.t; message_counter : Z.t}
 
 type output = {outbox_level : Bounded.Non_negative_int32.t; message_index : Z.t}
@@ -12099,7 +12103,7 @@ type info = {
 
 module Make
     (Tree : Context.TREE with type key = string list and type value = bytes) : sig
-  val initial_state : Tree.tree -> Tree.tree Lwt.t
+  val initial_state : version -> Tree.tree -> Tree.tree Lwt.t
 
   val install_boot_sector :
     ticks_per_snapshot:Z.t ->
diff --git a/src/lib_protocol_environment/sigs/v9/wasm_2_0_0.mli b/src/lib_protocol_environment/sigs/v9/wasm_2_0_0.mli
index e97eecc3ddddab86510765640a5f99fcb88d1975..a7107b945eb8d304d555292282e6460cc10347e5 100644
--- a/src/lib_protocol_environment/sigs/v9/wasm_2_0_0.mli
+++ b/src/lib_protocol_environment/sigs/v9/wasm_2_0_0.mli
@@ -23,6 +23,10 @@
 (*                                                                           *)
 (*****************************************************************************)
 
+type version
+
+val v0 : version
+
 type input = {inbox_level : Bounded.Non_negative_int32.t; message_counter : Z.t}
 
 type output = {outbox_level : Bounded.Non_negative_int32.t; message_index : Z.t}
@@ -44,7 +48,7 @@ type info = {
 
 module Make
     (Tree : Context.TREE with type key = string list and type value = bytes) : sig
-  val initial_state : Tree.tree -> Tree.tree Lwt.t
+  val initial_state : version -> Tree.tree -> Tree.tree Lwt.t
 
   val install_boot_sector :
     ticks_per_snapshot:Z.t ->
diff --git a/src/lib_scoru_wasm/constants.ml b/src/lib_scoru_wasm/constants.ml
index 3f51cf9c497ee21108784f4772f20f75bb2d66f9..18e1b599d44dffa2790a7cd81387f4d1b240b454 100644
--- a/src/lib_scoru_wasm/constants.ml
+++ b/src/lib_scoru_wasm/constants.ml
@@ -65,4 +65,6 @@ let too_many_reboot_flag_key =
 let reboot_counter_key =
   Durable.key_of_string_exn "/readonly/kernel/env/reboot_counter"
 
+let version_key = Durable.key_of_string_exn "/readonly/wasm_version"
+
 let stack_size_limit = 300
diff --git a/src/lib_scoru_wasm/helpers/wasm_utils.ml b/src/lib_scoru_wasm/helpers/wasm_utils.ml
index 25e39d418f862f2e04d5f9618fabb80833aa3a4e..640968a802ed8d215f61077340727ba2829ca565 100644
--- a/src/lib_scoru_wasm/helpers/wasm_utils.ml
+++ b/src/lib_scoru_wasm/helpers/wasm_utils.ml
@@ -61,7 +61,7 @@ let initial_tree ?(ticks_per_snapshot = default_max_tick)
   let open Lwt.Syntax in
   let max_tick_Z = Z.of_int64 ticks_per_snapshot in
   let* tree = empty_tree () in
-  let* tree = Wasm.initial_state tree in
+  let* tree = Wasm.initial_state V0 tree in
   let* boot_sector = if from_binary then Lwt.return code else wat2wasm code in
   let* tree =
     Wasm.install_boot_sector
diff --git a/src/lib_scoru_wasm/wasm_pvm.ml b/src/lib_scoru_wasm/wasm_pvm.ml
index e7069351e42dea6c2cc942dbe1914689371ab3ef..7c5b0e410ee44ca9b4b5e2495fb09fb69c9df5fc 100644
--- a/src/lib_scoru_wasm/wasm_pvm.ml
+++ b/src/lib_scoru_wasm/wasm_pvm.ml
@@ -28,6 +28,8 @@ open Wasm_pvm_state.Internal_state
 module Wasm = Tezos_webassembly_interpreter
 module Parsing = Binary_parser_encodings
 
+let durable_scope = ["durable"]
+
 let tick_state_encoding =
   let open Tezos_tree_encoding in
   tagged_union
@@ -110,7 +112,7 @@ let durable_buffers_encoding =
   Tezos_tree_encoding.(scope ["pvm"; "buffers"] Wasm_encoding.buffers_encoding)
 
 let durable_storage_encoding =
-  Tezos_tree_encoding.(scope ["durable"] Durable.encoding)
+  Tezos_tree_encoding.(scope durable_scope Durable.encoding)
 
 let default_buffers validity_period message_limit () =
   Tezos_webassembly_interpreter.Eval.
@@ -236,20 +238,29 @@ module Make_pvm (Wasm_vm : Wasm_vm_sig.S) (T : Tezos_tree_encoding.TREE) :
     let* tree = T.remove tree ["wasm"] in
     Tree_encoding_runner.encode pvm_state_encoding pvm_state tree
 
-  let initial_state empty_tree =
-    let version = Tezos_lazy_containers.Chunked_byte_vector.of_string "2.0.0" in
-    Tree_encoding_runner.encode
-      Tezos_tree_encoding.(
-        scope ["durable"; "readonly"; "wasm_version"; "@"] chunked_byte_vector)
-      version
-      empty_tree
+  let initial_state version empty_tree =
+    let open Lwt.Syntax in
+    let* durable =
+      Tree_encoding_runner.decode durable_storage_encoding empty_tree
+    in
+    let version_str =
+      Data_encoding.Binary.to_string_exn Wasm_pvm_state.version_encoding version
+    in
+    let* durable =
+      Durable.set_value_exn
+        ~edit_readonly:true
+        durable
+        Constants.version_key
+        version_str
+    in
+    Tree_encoding_runner.encode durable_storage_encoding durable empty_tree
 
   let install_boot_sector ~ticks_per_snapshot ~outbox_validity_period
       ~outbox_message_limit bs tree =
     let open Lwt_syntax in
     let open Tezos_tree_encoding in
     let* durable =
-      Tree_encoding_runner.decode (scope ["durable"] Durable.encoding) tree
+      Tree_encoding_runner.decode (scope durable_scope Durable.encoding) tree
     in
     let reboot_flag_key = Durable.key_of_string_exn "/kernel/env/reboot" in
     let kernel_key = Durable.key_of_string_exn "/kernel/boot.wasm" in
diff --git a/src/lib_scoru_wasm/wasm_pvm_sig.ml b/src/lib_scoru_wasm/wasm_pvm_sig.ml
index 4d41aa61c57054fcf1699b59a06f5f28c02462ef..5144289678f915f584d432615f54d072eab7342b 100644
--- a/src/lib_scoru_wasm/wasm_pvm_sig.ml
+++ b/src/lib_scoru_wasm/wasm_pvm_sig.ml
@@ -70,7 +70,7 @@ module type S = sig
 
   (** [initial_state empty_tree] computes the initial tree whose hash
       is hard-coded in the protocol. *)
-  val initial_state : tree -> tree Lwt.t
+  val initial_state : version -> tree -> tree Lwt.t
 
   (** [install_boot_sector ~ticks_per_snapshot ~output_validity_period payload
       tree] installs the [payload] passed as an argument in [tree] so that it is
diff --git a/src/lib_scoru_wasm/wasm_pvm_state.ml b/src/lib_scoru_wasm/wasm_pvm_state.ml
index d22e5564ebbe71984d0b40387baac258a682aaa4..cf4fe8c81aeb2e7bdd30fef4f8eafd82acf2a62c 100644
--- a/src/lib_scoru_wasm/wasm_pvm_state.ml
+++ b/src/lib_scoru_wasm/wasm_pvm_state.ml
@@ -24,6 +24,21 @@
 (*                                                                           *)
 (*****************************************************************************)
 
+type version = V0
+
+let version_encoding =
+  (* This encoding is directly used by the protocol. As a consequence,
+     any change done to it needs to be backward compatible!
+
+     We cannot use [string_enum] here because [string_enum] will
+     append the size of the string at the beginning of the encoded
+     bytes. *)
+  Data_encoding.(
+    conv_with_guard
+      (function V0 -> "2.0.0")
+      (function "2.0.0" -> Ok V0 | _ -> Error "not a valid version")
+      Variable.string)
+
 (** Represents the location of an input message. *)
 type input_info = {
   inbox_level : Tezos_base.Bounded.Non_negative_int32.t;
diff --git a/src/lib_store/unix/test/test_consistency.ml b/src/lib_store/unix/test/test_consistency.ml
index 7e0a2e993256b615bd9aa687553a4c9a5819bba6..9ec4db0498ad79d879ebdbf99e8264de4c06fed0 100644
--- a/src/lib_store/unix/test/test_consistency.ml
+++ b/src/lib_store/unix/test/test_consistency.ml
@@ -30,7 +30,7 @@ let nb_protocols = 5
 let register_protocol ~hash ~sources =
   let module M = struct
     include
-      Registered_protocol.Register_embedded_V8
+      Registered_protocol.Register_embedded_V9
         (Tezos_protocol_environment_demo_noops)
         (Tezos_protocol_demo_noops.Protocol)
         (struct
diff --git a/src/lib_tree_encoding/decoding.ml b/src/lib_tree_encoding/decoding.ml
index 9f139676e4b0fcdb1fe377d2003950d12ecaa333..d5f956c69206a0eba80f2acfb154556813276047 100644
--- a/src/lib_tree_encoding/decoding.ml
+++ b/src/lib_tree_encoding/decoding.ml
@@ -141,8 +141,24 @@ let value ?default key decoder =
 
 let subtree backend tree prefix =
   let open Lwt_syntax in
-  let+ tree = Tree.find_tree backend tree (prefix []) in
-  Option.map (Tree.wrap backend) tree
+  let tmp_directory = "tmp" in
+  let* subtree = Tree.find_tree backend tree (prefix []) in
+  let+ subtree =
+    match subtree with
+    | Some subtree -> return subtree
+    | None -> (
+        let* tree =
+          Tree.add backend tree (prefix [tmp_directory]) (Bytes.of_string "")
+        in
+        let* subtree = Tree.find_tree backend tree (prefix []) in
+        match subtree with
+        | Some subtree -> Tree.remove backend subtree [tmp_directory]
+        | None ->
+            (* This case is impossible, because we have added something
+               in the tree to avoid it. *)
+            assert false)
+  in
+  Tree.wrap backend subtree
 
 let scope key {decode} =
   {
@@ -162,7 +178,7 @@ let lazy_mapping to_key field_enc =
             input_prefix
         in
         let+ tree = subtree backend input_tree input_prefix in
-        (tree, produce_value));
+        (Some tree, produce_value));
   }
 
 let case_lwt tag decode extract = Case {tag; decode; extract}
@@ -209,8 +225,5 @@ let wrapped_tree =
       (fun backend tree prefix ->
         let open Lwt.Syntax in
         let+ tree = subtree backend tree prefix in
-        match tree with
-        | Some subtree ->
-            Tree.Wrapped_tree (Tree.select backend subtree, backend)
-        | _ -> raise Not_found);
+        Tree.Wrapped_tree (Tree.select backend tree, backend));
   }
diff --git a/src/proto_016_PtMumbai/lib_protocol/test/unit/test_sc_rollup_wasm.ml b/src/proto_016_PtMumbai/lib_protocol/test/unit/test_sc_rollup_wasm.ml
index 544e03dd212ce0aaf36ade50843aacdb2ce73a55..9a7f3dbca8d5d6195836baf0ae48c1ec1c50a91c 100644
--- a/src/proto_016_PtMumbai/lib_protocol/test/unit/test_sc_rollup_wasm.ml
+++ b/src/proto_016_PtMumbai/lib_protocol/test/unit/test_sc_rollup_wasm.ml
@@ -235,7 +235,7 @@ let test_output () =
     match parsed.it with Script.Textual m -> m | _ -> assert false
   in
   let*! boot_sector = Encode.encode parsed in
-  let*! tree = Wasm.initial_state empty_tree in
+  let*! tree = Wasm.initial_state V0 empty_tree in
   let*! tree =
     Wasm.install_boot_sector
       ~ticks_per_snapshot:Sc_rollup_wasm.V2_0_0.ticks_per_snapshot
diff --git a/src/proto_016_PtMumbai/lib_sc_rollup_node/wasm_2_0_0_pvm.ml b/src/proto_016_PtMumbai/lib_sc_rollup_node/wasm_2_0_0_pvm.ml
index 9a7170774a955c00d4f75580ba043640b56514cc..bc9abdd67d5a632626c6bfd2e91fdab75eaba7d3 100644
--- a/src/proto_016_PtMumbai/lib_sc_rollup_node/wasm_2_0_0_pvm.ml
+++ b/src/proto_016_PtMumbai/lib_sc_rollup_node/wasm_2_0_0_pvm.ml
@@ -62,8 +62,11 @@ module Make_wrapped_tree (Tree : TreeS) :
   let wrap t = PVM_tree t
 end
 
-module Make_backend (Tree : TreeS) =
-  Tezos_scoru_wasm_fast.Pvm.Make (Make_wrapped_tree (Tree))
+module Make_backend (Tree : TreeS) = struct
+  include Tezos_scoru_wasm_fast.Pvm.Make (Make_wrapped_tree (Tree))
+
+  let initial_state = initial_state V0
+end
 
 module Make_durable_state
     (T : Tezos_tree_encoding.TREE with type tree = Context.tree) :
diff --git a/src/proto_alpha/lib_protocol/sc_rollup_wasm.ml b/src/proto_alpha/lib_protocol/sc_rollup_wasm.ml
index bdc218943479fc1b899ee23c3cddd7d00476431b..1156d96954ceeeda5223e6e89110bd1870376eb2 100644
--- a/src/proto_alpha/lib_protocol/sc_rollup_wasm.ml
+++ b/src/proto_alpha/lib_protocol/sc_rollup_wasm.ml
@@ -81,6 +81,8 @@ let () =
     (fun () -> WASM_invalid_dissection_distribution)
 
 module V2_0_0 = struct
+  let current_version = Wasm_2_0_0.v0
+
   let ticks_per_snapshot = Z.of_int64 11_000_000_000L
 
   let outbox_validity_period = Int32.of_int 80_640
@@ -260,7 +262,7 @@ module V2_0_0 = struct
 
     open Monad
 
-    let initial_state ~empty = WASM_machine.initial_state empty
+    let initial_state ~empty = WASM_machine.initial_state current_version empty
 
     let install_boot_sector state boot_sector =
       WASM_machine.install_boot_sector
diff --git a/src/proto_alpha/lib_protocol/sc_rollup_wasm.mli b/src/proto_alpha/lib_protocol/sc_rollup_wasm.mli
index cb2291150b2ec5f486b15cfd65ff26358b91308b..72bfc145c2e3beb17ad6fbffad52270c20daa093 100644
--- a/src/proto_alpha/lib_protocol/sc_rollup_wasm.mli
+++ b/src/proto_alpha/lib_protocol/sc_rollup_wasm.mli
@@ -28,6 +28,8 @@ module V2_0_0 : sig
   (** This module provides Proof-Generating Virtual Machine (PVM) running
     WebAssembly (version 2.0.0). *)
 
+  val current_version : Wasm_2_0_0.version
+
   module type S = sig
     include Sc_rollup_PVM_sig.S
 
diff --git a/src/proto_alpha/lib_protocol/test/unit/test_sc_rollup_wasm.ml b/src/proto_alpha/lib_protocol/test/unit/test_sc_rollup_wasm.ml
index 544e03dd212ce0aaf36ade50843aacdb2ce73a55..115f6fc00cb7d6cada403e2520f190c658c25d44 100644
--- a/src/proto_alpha/lib_protocol/test/unit/test_sc_rollup_wasm.ml
+++ b/src/proto_alpha/lib_protocol/test/unit/test_sc_rollup_wasm.ml
@@ -235,7 +235,9 @@ let test_output () =
     match parsed.it with Script.Textual m -> m | _ -> assert false
   in
   let*! boot_sector = Encode.encode parsed in
-  let*! tree = Wasm.initial_state empty_tree in
+  let*! tree =
+    Wasm.initial_state Sc_rollup_wasm.V2_0_0.current_version empty_tree
+  in
   let*! tree =
     Wasm.install_boot_sector
       ~ticks_per_snapshot:Sc_rollup_wasm.V2_0_0.ticks_per_snapshot