Wasm bytecode could not be deserialized. Deserialization error: "bulk memory support is not enabled..."

[gRoussac]

Hi I am not sure it this interests you otherwise please close.

I am trying to deploy a contract on wasmd compiled with either stable rustc 1.87.0 (17067e9ac 2025-05-09) or nightly rustc 1.89.0-nightly (1677d46cb 2025-06-10)

[dependencies]
sylvia = "1.3.0"
cw-storage-plus = "2.0.0"
cosmwasm-schema = "2.0.2"

and I get this error

Error calling the VM: Error during static Wasm validation: Wasm bytecode could not be deserialized. Deserialization error: \"bulk memory support is not enabled (at offset 0x6a7)\": create wasm contract failed [CosmWasm/wasmd/x/wasm/keeper/keeper.go:189] with gas used: '1898453': unknown request"

cosmwasm-check ../target/wasm32-unknown-unknown/release/mycontract.wasm 
Available capabilities: {"cosmwasm_1_2", "cosmwasm_1_1", "iterator", "cosmwasm_2_2", "cosmwasm_1_3", "cosmwasm_1_4", "stargate", "cosmwasm_2_0", "cosmwasm_2_1", "staking"}

../target/wasm32-unknown-unknown/release/mycontract.wasm: failure
Error during static Wasm validation: Wasm bytecode could not be deserialized. Deserialization error: "bulk memory support is not enabled (at offset 0x86f)"

Passes: 0, failures: 1

I tried stable

RUSTFLAGS="-C target-feature=-bulk-memory" cargo build --release --target wasm32-unknown-unknown

but did not fix the issue which looks familiar with this CosmWasm/cosmwasm#1727

sylvia uses cargo wasm as config alias but actually what deploys is indeed as per CosmWasm/cosmwasm#2485 (comment)

RUSTFLAGS="-C target-cpu=mvp" cargo +nightly build -Zbuild-std=panic_abort,std --target wasm32-unknown-unknown --release --lib

nightly thus. Stable would fail like in CosmWasm/cosmwasm#2292

If someone has the same issue...

[chipshort]

You need to use a compatible Rust version. Version 1.81 is fully supported by the CosmWasm VM. Version 1.82 - 1.86 are supported if you use binaryen's wasm-opt afterwards (using the optimizer will do this for you). Later versions are currently not supported because of the bulk-memory issue you mentioned.

[gRoussac]

@chipshort Hi, thanks for your answer. Will try that. As far as I remember I believe I took the sylvia template as boilerplate, maybe specifying that in its doc https://github.com/hashedone/sylvia-template would be useful or maybe add a rust toolchain file pining 1.8.1 ?

Then please close issue if not planned to support thanks.