Regression in 2.9.0: TypeError in serializeQueryArgs after ~60s runtime

[milofrw]

After upgrading Redux Toolkit from 2.8.2 → 2.9.0, we’re encountering a runtime TypeError related to serializeQueryArgs.

This does not surface in type checking or during build, but it consistently appears at runtime after almost exactly 60 seconds.

Possible Cause - It looks like serializeQueryArgs is being called on an undefined endpointDefinition inside queryArgsApi.endpointDefinition.serializeQueryArgs.
This may be related to changes in RTK Query’s buildCreateApi defaults between 2.8.2 → 2.9.0.

Workaround - Downgrading back to 2.8.2 resolves the issue.

[markerikson]

Hmm. We definitely have a number of places that assume that endpointDefinitions[endpointName] should exist and don't check if it does.

Can you provide a repro for this?

[markerikson]

Still waiting for a repro so I can look into this.