DioxusLabs/dioxus · error

Failed to patch wasm module at {} - response failed with: {}

Error message

Failed to patch wasm module at {} - response failed with: {}

What it means

Subsecond's runtime hot-patcher fetched the replacement .wasm from the dev server and the HTTP response failed (non-OK status). The patch at the given library path cannot be applied without the patch module bytes, so the error reports the failing path and response.

Source

Thrown at packages/subsecond/subsecond/src/lib.rs:578

        let funcs: Table = wasm_bindgen::function_table().unchecked_into();
        let memory: Memory = wasm_bindgen::memory().unchecked_into();
        let exports: Object = wasm_bindgen::exports().unchecked_into();

        let path = table.lib.to_str().unwrap();
        if !path.ends_with(".wasm") {
            return;
        }

        // Fetch + decode the patch wasm. Both awaits are pure I/O — they
        // touch no shared state, so the future is safe to drop here.
        let response: web_sys::Response =
            JsFuture::from(web_sys::window().unwrap_throw().fetch_with_str(&path))
                .await
                .unwrap()
                .unchecked_into();
        if !response.ok() {
            panic!(
                "Failed to patch wasm module at {} - response failed with: {}",
                path,
                response.status_text()
            );
        }
        let dl_bytes: ArrayBuffer = JsFuture::from(response.array_buffer().unwrap())
            .await
            .unwrap()
            .unchecked_into();

        // Pre-compile. This is the slow part — V8 hands it to a worker —
        // and yields the longest. The result is a Module with no side
        // effects on host JS state, so cancelling here is also safe.
        let module: Module = JsFuture::from(WebAssembly::compile(dl_bytes.unchecked_ref()))
            .await
            .unwrap()
            .unchecked_into();

View on GitHub (pinned to 24f6a829df)

Solutions

1. The wasm patch request failed. Ensure dx serve is running and reachable, then rebuild and restart the dev server.

When it happens

Trigger: Thrown at packages/subsecond/subsecond/src/lib.rs:578 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of DioxusLabs/dioxus@24f6a829df (2026-08-23). Data as JSON: /api/errors/ab874b297c6fd2d2. Report an issue: GitHub.