Hey, thanks for the report. The ERROR_BAD_REQUEST often happens for two reasons - MCP servers and the Override OpenAI Base URL toggle.
Please check:
- Settings > MCP - disable all MCP servers and restart Cursor. This has helped before: Always show the error:Bad Request
- Settings > Models > API Keys - if custom keys are enabled, temporarily disable them. Make sure Override OpenAI Base URL is off. There’s a known bug with this toggle: API Keys for ChatGPT and Anthropic Failing
- Create a new chat and see if the error reproduces there.
If it doesn’t help, please send:
- Screenshots of Settings > MCP and Settings > Models > API Keys (showing enabled MCPs and the state of Override OpenAI Base URL)
- Confirmation whether it works in a new chat
- New Request IDs after trying with MCP off and Override Base URL off
- Console errors (Help > Toggle Developer Tools > Console) at the moment of the error
Let me know which step helped.