TypeError: RequestInit: Expected signal ("AbortSignal {}") to be an instance of AbortSignal.

[MarcMcIntosh]

Happens when using node v24.0.0, with vitest, msw and jsdom.

Full error

An unhandled error occurred processing a request for the endpoint "ping".
In the case of an unhandled error, no tags will be "provided" or "invalidated". TypeError: RequestInit: Expected signal ("AbortSignal {}") to be an instance of AbortSignal.
    at Object.webidl.errors.exception (node:internal/deps/undici/undici:4096:14)
    at Object.AbortSignal (node:internal/deps/undici/undici:4338:31)
    at node:internal/deps/undici/undici:10747:41
    at node:internal/deps/undici/undici:4389:16
    at Object.RequestInit (node:internal/deps/undici/undici:4371:21)
    at new Request (node:internal/deps/undici/undici:10111:34)
    at Object.construct (file:///Users/marc/Projects/refact/refact-agent/gui/node_modules/@mswjs/interceptors/src/interceptors/ClientRequest/utils/recordRawHeaders.ts:185:33)
    at file:///Users/marc/Projects/refact/refact-agent/gui/node_modules/@reduxjs/toolkit/src/query/fetchBaseQuery.ts:236:21
    at Object.queryFn (/Users/marc/Projects/refact/refact-agent/gui/src/services/refact/ping.ts:15:26)
    at executeRequest (file:///Users/marc/Projects/refact/refact-agent/gui/node_modules/@reduxjs/toolkit/src/query/core/buildThunks.ts:308:20)

passes with node version 22

[markerikson]

Can you provide an actual repro? That doesn't give much to go on.

[phryneas]

I would assume that you have some kind of AbortController polyfill in your application while undici requires you to use the node-native AbortController. Can you try to remove that polyfill?

[MarcMcIntosh]

@markerikson
sure it's in our CI https://github.com/smallcloudai/refact/actions/runs/14865630159/job/41742265895#step:5:2903
git clone cd /refact/refact-agent/gui && nvm use node && npm run test.

@phryneas I can try, I'll have to figure out where the polyfill is coming from 😅 (probably jsdom)

[louh]

I'm seeing this same issue in my application, and we have a very similar setup with Vitest and MSW. Test log is here: https://github.com/streetmix/streetmix/actions/runs/14998382595/job/42138378871#step:8:1338

One thing we have in common is we are both using the builder.query() method in createApi's endpoints configuration. (see https://github.com/smallcloudai/refact/blob/cc30e2ef580786da140fe452c2a10174c35cb22c/refact-agent/gui/src/services/refact/ping.ts#L8-L9 and https://github.com/streetmix/streetmix/blob/f7f38c4628198ed21618cd585093e2d312ff35b6/client/src/store/services/api.ts#L19-L20)

I am not intentionally polyfilling fetch either.

[kavsingh]

Ran into a similar issue with our application (closed source unfortunately so can't share a link, will try to get a repro up). We use toolkit and vitest, but not msw. Migrating our test env from jsdom to happy-dom resolved the issue - not an ideal solution but unblocked us from using node 24. These may be of interest: jsdom/jsdom#3682 (comment), jsdom/jsdom#3682 (comment)