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claude-code - 💡(How to fix) Fix [BUG] CLAUDE_CODE_DISABLE_EXPERIMENTAL_BETAS=1 is being ignored since v2.1.129

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Error Message

API Error: 400 vertex-ai error: Unexpected value(s) context-1m-2025-08-07 for the anthropic-beta header. Please consult our documentation at docs.anthropic.com or try again without the header.

Code Example

API Error: 400 vertex-ai error: Unexpected value(s) `context-1m-2025-08-07` for the `anthropic-beta` 
     header. Please consult our documentation at docs.anthropic.com or try again without the header.

---

"env": {
    [...]
    "CLAUDE_CODE_DISABLE_EXPERIMENTAL_BETAS": "1"
  },

---

API Error: 400 vertex-ai error: Unexpected value(s) `context-1m-2025-08-07` for the `anthropic-beta` 
     header. Please consult our documentation at docs.anthropic.com or try again without the header.
RAW_BUFFERClick to expand / collapse

Preflight Checklist

  • I have searched existing issues and this hasn't been reported yet
  • This is a single bug report (please file separate reports for different bugs)
  • I am using the latest version of Claude Code

What's Wrong?

On version v2.1.129-v2.1.32 I get the following error, when I try to have a conversation with claude:

API Error: 400 vertex-ai error: Unexpected value(s) `context-1m-2025-08-07` for the `anthropic-beta` 
     header. Please consult our documentation at docs.anthropic.com or try again without the header.

My settings.json contains:

  "env": {
    [...]
    "CLAUDE_CODE_DISABLE_EXPERIMENTAL_BETAS": "1"
  },

As far as I understand this should prevent claude from sending the anthrophic-beta header, but it doesn't prevent it anymore. v2.1.128 still works

What Should Happen?

Claude should not send anthropic-beta when environment variable CLAUDE_CODE_DISABLE_EXPERIMENTAL_BETAS=1

Error Messages/Logs

API Error: 400 vertex-ai error: Unexpected value(s) `context-1m-2025-08-07` for the `anthropic-beta` 
     header. Please consult our documentation at docs.anthropic.com or try again without the header.

Steps to Reproduce

  1. run claude: $ claude
  2. type anything in the interactive terminal > hi

Claude Model

None

Is this a regression?

Yes, this worked in a previous version

Last Working Version

2.1.128

Claude Code Version

2.1.132

Platform

Anthropic API

Operating System

Ubuntu/Debian Linux

Terminal/Shell

IntelliJ IDEA terminal

Additional Information

No response

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#api#environment variable#agent setup#task chaining#parallel task

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