I can't use Sonnet 4.5 for a while

[qqq1]

Where does the bug appear (feature/product)?

Cursor IDE

Describe the Bug

I can’t use specific models such as Claude Sonnet 4.5, and it has been continued for over 2 weeks.
Once I start using Claude Sonnet 4.5 this certain error happens.
As I need use Sonnet 4.5 for work, this error really makes me annoyed.

“An unexpected error occurred on our servers. Please try again, or contact support if the issue persists.”

The latest request id is below.

Steps to Reproduce

I have no idea if someone met the same error as me.

Operating System

Windows 10/11

Version Information

Version: 3.18.9 (user setup)
VS Code Extension API: 1.128.0
Commit: 2ba48ff3f7514cc4643c52ca9f7b3173d9b66130
Date: 2026-08-27T01:42:22.092Z
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.291
OS: Windows_NT x64 10.0.26100

For AI issues: which model did you use?

Sonnet4.5

For AI issues: add Request ID with privacy disabled

Request ID: be7f67f1-60b1-4f8a-9352-d19aa02ab4a5
[internal] Failed to run step, exceeded max retries
RetriableError: [internal] Failed to run step, exceeded max retries
at wwf (vscode-file://vscode-app/c:/Users/[UserName]/AppData/Local/Programs/cursor/resources/app/out/vs/workbench/workbench.desktop.main.js:8042:131644)
at tqs (vscode-file://vscode-app/c:/Users/[UserName]/AppData/Local/Programs/cursor/resources/app/out/vs/workbench/workbench.desktop.main.js:8042:130070)
at Gwf (vscode-file://vscode-app/c:/Users/[UserName]/AppData/Local/Programs/cursor/resources/app/out/vs/workbench/workbench.desktop.main.js:8043:13645)
at Object.classify (vscode-file://vscode-app/c:/Users/[UserName]/AppData/Local/Programs/cursor/resources/app/out/vs/workbench/workbench.desktop.main.js:8043:17843)
at Uwf (vscode-file://vscode-app/c:/Users/[UserName]/AppData/Local/Programs/cursor/resources/app/out/vs/workbench/workbench.desktop.main.js:8043:5924)
at async pqs.run (vscode-file://vscode-app/c:/Users/[UserName]/AppData/Local/Programs/cursor/resources/app/out/vs/workbench/workbench.desktop.main.js:8043:17165)
at async fce.runAgentLoop (vscode-file://vscode-app/c:/Users/[UserName]/AppData/Local/Programs/cursor/resources/app/out/vs/workbench/workbench.desktop.main.js:8143:34413)
at async qIo.streamFromAgentBackend (vscode-file://vscode-app/c:/Users/[UserName]/AppData/Local/Programs/cursor/resources/app/out/vs/workbench/workbench.desktop.main.js:17461:15117)
at async qIo.getAgentStreamResponse (vscode-file://vscode-app/c:/Users/[UserName]/AppData/Local/Programs/cursor/resources/app/out/vs/workbench/workbench.desktop.main.js:17461:34036)
at async qIe._submitChatMaybeAbortCurrent (vscode-file://vscode-app/c:/Users/[UserName]/AppData/Local/Programs/cursor/resources/app/out/vs/workbench/workbench.desktop.main.js:8121:4529)

• Masked username.

Does this stop you from using Cursor

No - Cursor works, but with this issue

[Colin]

Hi @qqq1, thanks for the report and the request ID!

Your Sonnet 4.5 requests are being rejected before the model generates anything because the prompt Cursor assembles for each message exceeds the roughly 200k tokens Sonnet 4.5 can accept. Cursor then tries to compress the conversation, retries, gets rejected again, and after a few rounds gives up with the “unexpected error” you see.

Typically you’ll find unexpected rules, skills, or MCP servers bloating the context window. To find out what exactly:

1. Open a new chat and select Sonnet 4.5.
2. Click the context usage percentage at the bottom of the chat input. It shows a breakdown by category. Whatever dominates on an empty chat is the culprit.

If you find you can’t get to this screen because the first chat never succeeds, try another model that works. The context usage should be about the same.

Let us know what you find!

[qqq1]

Thank you for replying. It works!

The reason is that there were too many rule files in different projects and the context within the whole workspace was over the limit size.