Where does the bug appear (feature/product)? Cursor IDE Describe the Bug When I am using “Override OpenAI Base URL” in settings, it makes agent with selected “Composer 2.5” model throw an error: This model does not support custom API keys This does not happen when “Auto” model selection is on. …

hey @vladpazych , you cannot use composer model or other non supported model via your api key when you turned on Overide OpenAI Base URL, this is by default, every call made to all model needs to pass through your OpenAI api sub, if you want to regain access to composer model and be billed via Cursor…

Hey, thanks for the report. This isn’t a bug, it’s the current by design behavior. Composer (1, 1.5, 2, 2.5) are Cursor’s own models, and they don’t work with BYOK keys. When OpenAI API Key / Override OpenAI Base URL is enabled, the key gets attached to all requests, including Composer, so you’ll s…

Composer 2.5 error "This model does not support custom API keys"

Support Bug Reports

Topic		Replies	Views
Composer 2.5 fails with BYOK Bug Reports byok , composer , linear-linked	4	95	July 3, 2026
Bug: Composer 2.5 explicitly selected requests blocked when OpenAI BYOK key is active Bug Reports byok , openai , composer , linear-linked	7	185	July 3, 2026
After overriding OpenAI api Composer does not work Bug Reports byok , composer	1	69	April 13, 2026
Composer 2 broken when custom OpenAI API Key is enabled Bug Reports byok , openai , composer	10	588	June 16, 2026
"Bad request: This model does not support custom APIs" when using Composer 2 with an OpenAI key configured Bug Reports byok , openai , composer	1	463	April 28, 2026

Composer 2.5 error "This model does not support custom API keys"

Related topics