dotnet/runtime · critical · Error

Mismatched git hashes between loader and runtime. Loader: ${

Error message

Mismatched git hashes between loader and runtime. Loader: ${runtimeApi.runtimeBuildInfo.gitHash}, Runtime: ${GitHash}

What it means

The interop module compares the loader's runtimeBuildInfo.gitHash against its own compiled-in GitHash constant (consts:gitHash). A mismatch means the interop JS bundle and the runtime/loader were built from different source revisions, which would break the JSImport/marshaler ABI, so initialization aborts.

Source

Thrown at src/native/libs/System.Runtime.InteropServices.JavaScript.Native/interop/index.ts:36

import { cancelPromise } from "./cancelable-promise";
import { loadLazyAssembly, loadSatelliteAssemblies } from "./lazy";
import { jsInteropState } from "./marshal";
import { initializeScheduling, abortInteropTimers } from "./scheduling";
import { wsAbort, wsClose, wsCreate, wsGetState, wsOpen, wsReceive, wsSend } from "./web-socket";
import {
    httpSupportsStreamingRequest, httpSupportsStreamingResponse, httpCreateController, httpGetResponseType,
    httpGetResponseStatus, httpAbort, httpTransformStreamWrite, httpTransformStreamClose, httpFetch,
    httpFetchStream, httpFetchBytes, httpGetResponseHeaderNames, httpGetResponseHeaderValues, httpGetResponseBytes,
    httpGetResponseLength, httpGetStreamedResponseBytes,
} from "./http";

export function dotnetInitializeModule(internals: InternalExchange): void {
    if (!Array.isArray(internals)) throw new Error("Expected internals to be an array");
    const runtimeApi = internals[InternalExchangeIndex.RuntimeAPI];
    if (typeof runtimeApi !== "object") throw new Error("Expected internals to have RuntimeAPI");

    if (runtimeApi.runtimeBuildInfo.gitHash && runtimeApi.runtimeBuildInfo.gitHash !== GitHash) {
        throw new Error(`Mismatched git hashes between loader and runtime. Loader: ${runtimeApi.runtimeBuildInfo.gitHash}, Runtime: ${GitHash}`);
    }

    const runtimeApiLocal: Partial<RuntimeAPI> = {
        getAssemblyExports,
        setModuleImports,
    };
    Object.assign(runtimeApi, runtimeApiLocal);
    Object.assign(runtimeApi.INTERNAL, {
        hasProperty,
        getTypeOfProperty,
        getProperty,
        setProperty,
        getGlobalThis,
        getDotnetInstance,
        dynamicImport,
        bindCsFunction,
        loadSatelliteAssemblies,
        loadLazyAssembly,

View on GitHub (pinned to 290d5ab72c)

Solutions

Clean rebuild + republish so the interop bundle and runtime share the same git hash/SDK.
Cache-bust all dotnet artifacts together — versioned folder or content-hash in URL.
Verify no service worker/CDN is serving a stale interop.js alongside a new runtime.

Example fix

// before: interop.js cached at v7 while runtime is v8
// after: bust cache, serve all bundles from /8.0.x/

Defensive patterns

Strategy: validation

Validate before calling

const loaderHash = runtimeApi.runtimeBuildInfo?.gitHash;
if (loaderHash && loaderHash !== GitHash) {
  throw new Error("Refusing init: interop/runtime git hash mismatch — republish with a matching build");
}

Try / catch

try { dotnetInitializeModule(internals); }
catch (e) {
  if (/Mismatched git hashes/.test(e.message)) purgeCacheAndReload();
  else throw e;
}

Prevention

Serve all dotnet bundles from one versioned folder.
Purge CDN/service-worker caches on every release.
Validate git-hash agreement before init in custom hosts.

When it happens

Trigger: Loading an interop bundle from one commit while the runtime/loader carries a different runtimeBuildInfo.gitHash.

Common situations: Partial deploy of dotnet bundles; CDN/browser cache mixing an old interop.js with a new runtime; local dev across repos with mismatched builds.

Related errors

AI-assisted analysis of dotnet/runtime@290d5ab72c (2026-08-06). Data as JSON: /api/errors/9e6472c6fc9bb250. Report an issue: GitHub.