Claude-fable-5 stopped working in Cursor with my own API key

Where does the bug appear (feature/product)?

Cursor IDE

Describe the Bug

I’m using claude-fable-5 with my own API key in Cursor. It was working fine until a few hours ago, but it suddenly stopped and now returns the error below. The same API key works perfectly with claude-fable-5 when called outside of Cursor, so I suspect that something in the request parameters Cursor sends to Claude conflicts with the non-ZDR 30-day retention policy. Updating to the latest version did not solve anything.

I’ve been a heavy Cursor user since the very beginning and have even taught it to many of my students, so it’s really disappointing and frustrating that Fable 5 fails only inside Cursor. Could you please look into this and fix it?
Error message:
We encountered an issue when using your API key: Provider was unable to process your request
API Error:
Request failed with status code 400: {“error”:{“type”:“client”,“reason”:“routing_unsupported”,“message”:“claude-fable-5 routing failed: requires non-ZDR provider policy”,“retryable”:false}}

Steps to Reproduce

Setup your own claude API key
Set the model to claude fable 5
Prompt anything from the IDE

Operating System

Windows 10/11

Version Information

Cursor IDE 3.7.27

Does this stop you from using Cursor

Yes - Cursor is unusable

1 Like

5 posts were merged into an existing topic: Claude-fable-5 fails with routing_unsupported (requires non-ZDR provider policy) even with own API key — direct API call succeeds