Cant switch from gemini to sonnet max mode

[jonah_adler]

Where does the bug appear (feature/product)?

Cursor IDE

Describe the Bug

Cant switch from gemini to sonnet 4.5 max

Steps to Reproduce

If I run the standard (non -background) agent with Gemini 2.5 Pro (max or non max)

and then follow up with sonnet 4.5 max mode

i get

We’re having trouble connecting to the model provider. This might be temporary - please try again in a moment.
(Request ID: 6c9b2069-d419-4792-bf60-bdadc6c50a21)

If i switch sonnet to non max mode it works

Have not tested with all model combos, but this one fails every time

Expected Behavior

I can switch

Operating System

MacOS

Current Cursor Version (Menu → About Cursor → Copy)

Version: 1.7.54
VSCode Version: 1.99.3
Commit: 5c17eb2968a37f66bc6662f48d6356a100b67be0
Date: 2025-10-21T19:07:38.476Z (1 wk ago)
Electron: 34.5.8
Chromium: 132.0.6834.210
Node.js: 20.19.1
V8: 13.2.152.41-electron.0
OS: Darwin arm64 24.6.0

For AI issues: add Request ID with privacy disabled

6c9b2069-d419-4792-bf60-bdadc6c50a21

Does this stop you from using Cursor

No - Cursor works, but with this issue

[deanrie]

Hey, thanks for the report.

Before we escalate, can you check if a custom OpenAI API key is enabled in Cursor Settings > Models > API Keys? There’s a known issue where custom keys can break other model providers.

If it’s enabled, try turning it off temporarily and see if that fixes the switching issue.

If you don’t have a custom key enabled, or turning it off doesn’t help, this looks like a bug we should investigate. Let me know what you find!

[jonah_adler]

Not enabled

[jonah_adler]

Note that i updated cursor and still see same issue.

Also have had this issue for at least 3-4 weeks (in case helpful for debugging). If I had to guess, it started when 4.5 sonnet was initially released.

[deanrie]

Thanks for confirming there’s no custom API key. Since this has been happening for weeks, let’s run diagnostics:

Network diagnostics:

• Open Cursor Settings → Network → click “Run Diagnostics”
• Share the results here

Disable HTTP/2:

• Press CMD + , → search “HTTP/2” → turn on “Disable HTTP/2”
• Restart Cursor and test the same model switch

Quick test:

• Does it happen if you start a fresh chat with Sonnet 4.5 Max directly, or only when switching models mid‑conversation?

Let me know what you find!