GPT-5.5 BYOK not working

Support Bug Reports
, ,
4

Hey, before filing this as a bug, we should narrow down the cause. User Provided API Key Rate Limit Exceeded is usually a wrapper around a 429 returned by the upstream provider, not a client-side block by Cursor. A few questions:

  1. Can your backend see the request in the logs when you try to send gpt-5.5? This is the most important one. If the request reaches the backend and the backend itself returns 429, it’s a quotas or limits issue on the provider side. If the request never reaches the backend at all, then yeah, Cursor might be ignoring the override somewhere.

  2. Did you add gpt-5.5 to Custom Model Names in Settings → Models → the list under Override OpenAI Base URL? Or are you picking gpt-5.5 from the default catalog? The BYOK override only applies to models explicitly added to the custom list. If gpt-5.4 is in that list but gpt-5.5 isn’t, that would explain the difference. A screenshot of that screen would help a lot.

  3. What exact model string did you enter? gpt-5.5, gpt-5.5-chat-latest, or something else?

  4. What kind of backend is behind the base URL? LiteLLM, OpenRouter, Azure, or self-hosted. No need to share the actual URL.

  5. Is Privacy Mode enabled?

Related thread about not being able to add gpt-5.5 as a custom model: Custom model addition failed. You might be hitting the same issue, just with a different symptom.