Stream: git-wasmtime

Topic: wasmtime / issue #12223 Failed to parse WebAssembly modul...

Wasmtime GitHub notifications bot (Dec 28 2025 at 00:02):

LeoBorai opened issue #12223:

Hi folks from Bytecode Alliance,

I'm writing a solution where I'm running wasm32-wasip2 async function via
wasmtime.

I have Rust code I'm compiling to WASM using the following command:

cargo +nightly build --release --target wasm32-wasip2

Then I grab the wasm file in:

target/wasm32-wasip2/release/http.wasm

And execute it via the following wasmtime instance:

https://github.com/LeoBorai/mate/blob/a83f164948ad6c349618c781df4ef1564d3d04c2/src/runner/src/lib.rs#L46

But when I run it, I'm getting the following error:

Error: failed to parse WebAssembly module

Caused by:
    `waitable.join` requires the component model async feature (at offset 0x8be71)

I've checked on features already, I see the feature component-model-async is
enabled (_Which comes as part of the default features so should be redundant at this point_).

Wasmtime GitHub notifications bot (Dec 28 2025 at 07:19):

bjorn3 commented on issue #12223:

Does config.wasm_component_model_async(true).wasm_component_model_async_builtins(true) work?

Wasmtime GitHub notifications bot (Dec 28 2025 at 17:01):

LeoBorai commented on issue #12223:

Hi @bjorn3, thank you so much for the suggestion. I've updated my code for the wasmtime instance to use the wasm_component_model_async/_builtins methods and the previous error not being printed anymore.

I will leave the snippet for the record:

         let mut config = Config::new();
-        config.async_support(true);
+        config
+            .async_support(true)
+            .wasm_component_model_async(true)
+            .wasm_component_model_async_builtins(true);
         let engine = Engine::new(&config)?;
         let mut linker = Linker::new(&engine);

Link to changes

Wasmtime GitHub notifications bot (Dec 28 2025 at 17:01):

LeoBorai closed issue #12223:

Hi folks from Bytecode Alliance,

I'm writing a solution where I'm running wasm32-wasip2 async function via
wasmtime.

I have Rust code I'm compiling to WASM using the following command:

cargo +nightly build --release --target wasm32-wasip2

Then I grab the wasm file in:

target/wasm32-wasip2/release/http.wasm

And execute it via the following wasmtime instance:

https://github.com/LeoBorai/mate/blob/a83f164948ad6c349618c781df4ef1564d3d04c2/src/runner/src/lib.rs#L46

But when I run it, I'm getting the following error:

Error: failed to parse WebAssembly module

Caused by:
    `waitable.join` requires the component model async feature (at offset 0x8be71)

I've checked on features already, I see the feature component-model-async is
enabled (_Which comes as part of the default features so should be redundant at this point_).

Last updated: Jan 09 2026 at 13:15 UTC