Kimi own key usage error

Support Bug Reports
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1

Where does the bug appear (feature/product)?

Cursor IDE

Describe the Bug

When I use my own API key, I get the following error. (Kimi-2.6)

Request ID: f8e77e31-d5ef-49af-8b1c-e46a6d6359f3
{“error”:“ERROR_PROVIDER_ERROR”,“details”:{“title”:“Provider Error”,“detail”:“Provider returned error: {"error":{"message":"thinking is enabled but reasoning_content is missing in assistant tool call message at index 3","type":"invalid_request_error"}}”,“isRetryable”:false,“additionalInfo”:{},“buttons”:,“planChoices”:},“isExpected”:true}
Provider Error Provider returned error: {“error”:{“message”:“thinking is enabled but reasoning_content is missing in assistant tool call message at index 3”,“type”:“invalid_request_error”}}
des: Provider Error Provider returned error: {“error”:{“message”:“thinking is enabled but reasoning_content is missing in assistant tool call message at index 3”,“type”:“invalid_request_error”}}
at g8y (vscode-file://vscode-app/Applications/Cursor.app/Contents/Resources/app/out/vs/workbench/workbench.desktop.main.js:28853:25419)
at p8y (vscode-file://vscode-app/Applications/Cursor.app/Contents/Resources/app/out/vs/workbench/workbench.desktop.main.js:28853:24303)
at C8y (vscode-file://vscode-app/Applications/Cursor.app/Contents/Resources/app/out/vs/workbench/workbench.desktop.main.js:28854:6490)
at e4d.run (vscode-file://vscode-app/Applications/Cursor.app/Contents/Resources/app/out/vs/workbench/workbench.desktop.main.js:28854:11311)
at async Ups.runAgentLoop (vscode-file://vscode-app/Applications/Cursor.app/Contents/Resources/app/out/vs/workbench/workbench.desktop.main.js:41180:14333)
at async C0h.streamFromAgentBackend (vscode-file://vscode-app/Applications/Cursor.app/Contents/Resources/app/out/vs/workbench/workbench.desktop.main.js:41248:12259)
at async C0h.getAgentStreamResponse (vscode-file://vscode-app/Applications/Cursor.app/Contents/Resources/app/out/vs/workbench/workbench.desktop.main.js:41248:19484)
at async Mbt.submitChatMaybeAbortCurrent (vscode-file://vscode-app/Applications/Cursor.app/Contents/Resources/app/out/vs/workbench/workbench.desktop.main.js:28969:17002)
at async za (vscode-file://vscode-app/Applications/Cursor.app/Contents/Resources/app/out/vs/workbench/workbench.desktop.main.js:40232:4234)

Steps to Reproduce

When I use my own API key, it works in agent mode as long as the K2.6 model is selected.

Operating System

MacOS

Version Information

Version: 3.3.4 (Universal)
VSCode Version: 1.105.1
Commit: e7262be617643fb2bd412dfdcca2ed82b21d0fa0
Date: 2026-05-03T00:48:29.057Z
Layout: editor
Build Type: Stable
Release Track: Nightly
Electron: 39.8.1
Chromium: 142.0.7444.265
Node.js: 22.22.1
V8: 14.2.231.22-electron.0
OS: Darwin arm64 25.4.0

For AI issues: which model did you use?

Kimi K2.6

Does this stop you from using Cursor

Sometimes - I can sometimes use Cursor

5

Hey, this is a known BYOK bug for providers that require reasoning_content passback like Kimi K2.6, DeepSeek V4, and similar. The first turn works, but on the next tool calls the provider returns 400 “thinking is enabled but reasoning_content is missing”. The same issue is discussed here: Kimi 2.6 custom model - Provider returned error: {"error":{"message":"thinking is enabled but reasoning_content is missing

We’re tracking it, but there’s no ETA for a fix yet. I grabbed the Request ID and I’ll link it to the ticket.

As a workaround, you can temporarily use the non-thinking Kimi option where reasoning passback isn’t required, or use another model in agent mode with tool calls. I’ll follow up once there’s an update.