[BUG] CLAUDE_CODE_DISABLE_EXPERIMENTAL_BETAS doesn't remove ?beta=true query params and anthropic-beta headers

Found 3 possible duplicate issues:

1. https://github.com/anthropics/claude-code/issues/11678
2. https://github.com/anthropics/claude-code/issues/12122
3. https://github.com/anthropics/claude-code/issues/11154

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🤖 Generated with Claude Code

Experiencing the same with Anthropic Models through Databricks

another hacky workaround is to set up a local proxy server that strips the query parameter and beta header from all outbound requests to anthropic API. you can get claude-code to spin one up for you really easily if you don't feel like writing one yourself...

Any update on this?

For me (using a proxy to Bedrock) this issue appeared when version 2.1.23 was rolled out. Version 2.1.22 still seems to work though.
So if you used the native install method on Mac & want to rollback:
curl -fsSL https://claude.ai/install.sh | bash -s -- 2.1.22

Source

Confirming @TilmannF : 2.1.22 works fine, but 2.1.23 is failing. Just in case you want to rollback to 2.1.22 the NPM way: npm install -g @anthropic-ai/claude-code@2.1.22

I have also the same issue with the Claude CLI with the new version 2.1.23

FWIW, recent reports are completely unrelated to MCP usage at all, v2.1.23 is just broken in regard to AWS Bedrock.

Also, my original workaround with sed won't work anymore.

Still happening in 2.1.25, specifically header structured-outputs-2025-12-15 does not work with Vertex but is still being sent by Claude Code even with CLAUDE_CODE_DISABLE_EXPERIMENTAL_BETAS=1

Still happening in 2.1.25，please quick quick repair.

In version 2.1.25, adding the global variable CLAUDE_CODE_DISABLE_EXPERIMENTAL_BETAS=1 worked, but I’m not sure if it’s possible to write an Nginx filter to remove parameters—it feels like it would be very troublesome.

Issue is resolved in https://github.com/anthropics/claude-code/releases/tag/v2.1.25

You only fixed part of the issue.

In 2.1.22 I see errors about structured-outputs-2025-12-15 beta headers, but it doesn't break the main Claude Code workflow. let's call it BUG_MINOR
In 2.1.23 Claude Code can't even start, lets call it BUG_MAJOR
In 2.1.25 you fixed BUG_MAJOR but not BUG_MINOR, I still see errors about structured-outputs-2025-12-15 when sending messages to vertex. Even with CLAUDE_CODE_DISABLE_EXPERIMENTAL_BETAS=1

Still seeing this issue. We weren't seeing this yesterday with 2.1.22.

LiteLLM, Claude Code, Bedrock

As of about 1400 GMT today, we've started seeing the invalid beta flag coming from the bedrock back end. Presumably the DISABLE_EXPERIMENTAL_BETAS flag shouldn't be needed, and this is something that needs fixing properly? Has a beta feature flag been deprecated recently?

Well, this issue was about CLAUDE_CODE_DISABLE_EXPERIMENTAL_BETAS=1 not being respected, and v2.1.25 resolves that in our context (LiteLLM proxying to AWS Bedrock).

PS: I'm just a user here.

Fair point - will raise a separate issue if one doesn't already exist.

Yeah, I can also confirm the issue is resolved for me now.

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