Unable to use databricks gpt 5.5 on cursor

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1

Where does the bug appear (feature/product)?

Cursor IDE

Describe the Bug

I configured databricks cding agents as per the doc here Integrate with coding agents | Databricks on AWS. I set the OpenAI Base URL and Model in the Cursor IDE under Settings → Models → API Keys. I am trying to call a AI gateway endpoint that calls the databricks hosted gpt 5.5. All other model works well except for 5.5 and i get this error Provider was unable to process your request. API Error: Request failed with status code 400: {“error”:{“type”:“client”,“reason”:“routing_unsupported”,“message”:“gpt-5.5 routing failed: GPT-5.5 routing only supports Responses-compatible requests”,“retryable”:false}}

I noticed there was a dicussion here Cursor cannot connect to a custom URL compatible with the OpenAI protocol

However i dont see a release for this yet

Steps to Reproduce

Use the gateway endpoint custom URL
Provide the API key
Create a gateway endpoint in Databricks
Add the endpoint as a custom model
Prompt the model

Operating System

MacOS

Version Information

Version: 3.7.19
VS Code Extension API: 1.105.1
Commit: 80c653c2c3528e65016a0d304b54486084b470b0
Date: 2026-06-07T01:42:56.126Z
Layout: glass
Build Type: Stable
Release Track: Default
Electron: 39.8.1
Chromium: 142.0.7444.265
Node.js: 22.22.1
V8: 14.2.231.22-electron.0
xterm.js: 6.1.0-beta.256
OS: Darwin arm64 25.5.0

Does this stop you from using Cursor

Yes - Cursor is unusable

6

Hi Sanjay, thanks for the detailed report.

This is a known GPT-5.5 + custom OpenAI Base URL issue. GPT-5.5 is sent in OpenAI’s Responses API format (input), but for a custom base URL Cursor still POSTs to the …/chat/completions path — so your Databricks gateway rejects the mismatch (GPT-5.5 routing only supports Responses-compatible requests). gpt-5.4 / gpt-5.4-mini skip that conversion, which is why they work.

Best thing to do is to use either a Cursor native model from the model picker or a gpt-5.4 model with databricks as that sounds like it is working sufficiently. I’ve added your report to our backlog tracking software so we can let you know any updates regarding this.

9

Hey @Sanjay_Ashok,

This issue should be fixed now. Could you give GPT-5.5 through your gateway another try and let me know if it’s working now?