Custom model with custom Base URL incorrectly shows “This model does not support custom API keys”

Support Bug Reports
1

Where does the bug appear (feature/product)?

Cursor IDE

Describe the Bug

I’m using a custom API endpoint in Cursor with a custom Base URL and a custom model name.

My current configuration is approximately:

  • Custom Base URL: enabled
  • Custom API Key: enabled
  • Model name: cx/gpt-5.6-sol-max

However, when I try to use this model, Cursor shows the following error:

This model does not support custom API keys.

This seems incorrect because cx/gpt-5.6-sol-max is a custom model served through my own OpenAI-compatible API endpoint. The API key and Base URL are both provided by me, rather than using Cursor’s built-in model provider.

Steps to Reproduce

  1. Open Cursor Settings.
  2. Configure a custom OpenAI-compatible Base URL.
  3. Configure a custom API key.
  4. Add a custom model with the name:
    cx/gpt-5.6-sol-max
  5. Select the model in Cursor.
  6. Try to send a request.
  7. Cursor displays:
    This model does not support custom API keys.

Expected Behavior

When a custom Base URL is configured, Cursor should send the configured model name directly to the custom OpenAI-compatible endpoint using the provided custom API key.

Cursor should not reject the model based on whether the model name matches one of Cursor’s built-in models.

In other words, a model such as:

cx/gpt-5.6-sol-max

should be treated as an arbitrary model identifier belonging to the custom API endpoint.

Operating System

Linux

Version Information

Version: 3.12.30
VS Code Extension API: 1.128.0
Commit: 63a2996a10d9e476b6c28e951dd7691d9c0cf480
Date: 2026-07-21T22:50:03.568Z
Layout: IDE
Build Type: Stable
Release Track: Default
Electron: 40.10.3
Chromium: 144.0.7559.236
Node.js: 24.15.0
V8: 14.4.258.32-electron.0
xterm.js: 6.1.0-beta.256
OS: Linux x64 6.17.0-22-generic

Does this stop you from using Cursor

Yes - Cursor is unusable

5

Hey, thanks for the detailed report. This isn’t anything in your setup. We’re tracking this issue. It happens when a custom model name contains the name of a built-in Cursor model inside it, in your case gpt-5.6-sol inside cx/gpt-5.6-sol-max. Because of that, the request incorrectly hits the guard “This model does not support custom API keys”, even though the key and Base URL are yours.

Workaround, if your gateway supports it: give the custom model a name that doesn’t overlap with built-in model names, so avoid substrings like gpt-5.6-sol, gpt-5.6-terra, etc. From your config, your other custom models with neutral names like glm-cn/..., oc/... work through the same endpoint without issues, so renaming or using an alias usually fixes it.

We’ll ship a proper fix on our side, but I can’t share an ETA yet. I’ll post in the thread when there’s an update. If renaming doesn’t work for you or doesn’t help, let me know.