claude-code - 💡(How to fix) Fix [BUG] Opus 4.7 on Bedrock fails with 'invalid beta flag' — Claude Code sends deprecated thinking API format [4 comments, 4 participants]

ironmano-csco · 2026-04-16T20:10:56Z

[claude-code] Preflight Checklist - x I have searched existing issues https://github.com/anthropics/claude-code/issues?q=is%3Aissue%20state%3Aopen%20label%3Abu… ## Fix / Workaround **Workarounds attempted (none worked):** - `CLAUDE_CODE_DISABLE_EXPERIMENTAL_BETAS=1` — does not strip `interleaved-thinking-2025-05-14` from the body - Changing `effortLevel` — no effect on the beta flag in the body ### Preflight Checklist - [x] I have searched [existing issues](https://github.com/anthropics/claude-code/issues?q=is%3Aissue%20state%3Aopen%20label%3Abug) and this hasn't been reported yet - [x] This is a single bug report (please file separate reports for different bugs) - [x] I am using the latest version of Claude Code ### What's Wrong? Claude Code v2.1.111 fails with a 400 "invalid beta flag" error when using Opus 4.7 (`us.anthropic.claude-opus-4-7`) on AWS Bedrock. **Root cause:** Opus 4.7 (released April 16, 2026) introduced a breaking change to the thinking API: - **Old (no longer supported by Opus 4.7):** `thinking.type: "enabled"` with `budget_tokens` + `anthropic_beta: ["interleaved-thinking-2025-05-14"]` - **New (required by Opus 4.7):** `thinking.type: "adaptive"` with `output_config: {effort: "high"}` — no beta flag needed Claude Code v2.1.111 still sends the old format to Bedrock's InvokeModel API: ``` body.anthropic_beta: ["interleaved-thinking-2025-05-14"] ← rejected by Opus 4.7 body.thinking: {type: "enabled", budget_tokens: ...} ← not supported by Opus 4.7 ``` Verified via direct AWS CLI calls: - Opus 4.7 works on Bedrock **without** beta flags (basic messages succeed) - Opus 4.7 works with `thinking.type: "adaptive"` + `output_config.effort` - Opus 4.7 **rejects** `anthropic_beta: ["interleaved-thinking-2025-05-14"]` with "invalid beta flag" - Opus 4.7 **rejects** `thinking.type: "enabled"` with: `"thinking.type.enabled" is not supported for this model. Use "thinking.type.adaptive" and "output_config.effort" to control thinking behavior.` ### What Should Happen? Claude Code should detect Opus 4.7 on Bedrock and use the new adaptive thinking API format instead of the deprecated enabled/budget_tokens format. ### Error Messages/Logs ``` ANTHROPIC_LOG=debug output: headers: { "anthropic-beta": "claude-code-20250219,effort-2025-11-24", } body: { thinking: [Object ...], anthropic_beta: [ "interleaved-thinking-2025-05-14" ], } API Error: 400 {"type":"error","request_id":"req_...","error":{"type":"invalid_request_error","message":"invalid beta flag"}} ``` ### Steps to Reproduce 1. Configure Claude Code for Bedrock with Opus 4.7: ```json { "env": { "CLAUDE_CODE_USE_BEDROCK": "1", "AWS_REGION": "us-west-2", "ANTHROPIC_MODEL": "us.anthropic.claude-opus-4-7" } } ``` 2. Start Claude Code: `claude` 3. Send any message — immediately fails with "invalid beta flag" **Workarounds attempted (none worked):** - `CLAUDE_CODE_DISABLE_EXPERIMENTAL_BETAS=1` — does not strip `interleaved-thinking-2025-05-14` from the body - Changing `effortLevel` — no effect on the beta flag in the body ### Claude Model Opus ### Is this a regression? No — Opus 4.7 is a new model released today (April 16, 2026) with breaking API changes ### Claude Code Version 2.1.111 (Claude Code) ### Platform AWS Bedrock Commercial ### Operating System macOS ### Terminal/Shell zsh ### Additional Information - Model `anthropic.claude-opus-4-7` is available and listed via `aws bedrock list-foundation-models` - Direct API calls via AWS CLI to `us.anthropic.claude-opus-4-7` work correctly without beta flags - Opus 4.6 (`anthropic.claude-opus-4-6-v1`) continues to work fine with Claude Code - The first-party Anthropic API likely handles this correctly since `opus` alias resolves to 4.7 there; the issue is specific to the Bedrock InvokeModel path

claude-code2026-04-16 20:10:56

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anthropics/claude-code#49490•Fetched 2026-04-17 08:39:41

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Error Message

ANTHROPIC_LOG=debug output:

headers: { "anthropic-beta": "claude-code-20250219,effort-2025-11-24", } body: { thinking: [Object ...], anthropic_beta: [ "interleaved-thinking-2025-05-14" ], }

API Error: 400 {"type":"error","request_id":"req_...","error":{"type":"invalid_request_error","message":"invalid beta flag"}}

Root Cause

Root cause: Opus 4.7 (released April 16, 2026) introduced a breaking change to the thinking API:

Fix Action

Fix / Workaround

Workarounds attempted (none worked):

CLAUDE_CODE_DISABLE_EXPERIMENTAL_BETAS=1 — does not strip interleaved-thinking-2025-05-14 from the body
Changing effortLevel — no effect on the beta flag in the body

Code Example

body.anthropic_beta: ["interleaved-thinking-2025-05-14"]   ← rejected by Opus 4.7
body.thinking: {type: "enabled", budget_tokens: ...}       ← not supported by Opus 4.7

---

ANTHROPIC_LOG=debug output:

headers: {
  "anthropic-beta": "claude-code-20250219,effort-2025-11-24",
}
body: {
  thinking: [Object ...],
  anthropic_beta: [ "interleaved-thinking-2025-05-14" ],
}

API Error: 400
{"type":"error","request_id":"req_...","error":{"type":"invalid_request_error","message":"invalid beta flag"}}

---

{
     "env": {
       "CLAUDE_CODE_USE_BEDROCK": "1",
       "AWS_REGION": "us-west-2",
       "ANTHROPIC_MODEL": "us.anthropic.claude-opus-4-7"
     }
   }

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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?

Claude Code v2.1.111 fails with a 400 "invalid beta flag" error when using Opus 4.7 (us.anthropic.claude-opus-4-7) on AWS Bedrock.

Root cause: Opus 4.7 (released April 16, 2026) introduced a breaking change to the thinking API:

Old (no longer supported by Opus 4.7): thinking.type: "enabled" with budget_tokens + anthropic_beta: ["interleaved-thinking-2025-05-14"]
New (required by Opus 4.7): thinking.type: "adaptive" with output_config: {effort: "high"} — no beta flag needed

Claude Code v2.1.111 still sends the old format to Bedrock's InvokeModel API:

body.anthropic_beta: ["interleaved-thinking-2025-05-14"]   ← rejected by Opus 4.7
body.thinking: {type: "enabled", budget_tokens: ...}       ← not supported by Opus 4.7

Verified via direct AWS CLI calls:

Opus 4.7 works on Bedrock without beta flags (basic messages succeed)
Opus 4.7 works with thinking.type: "adaptive" + output_config.effort
Opus 4.7 rejects anthropic_beta: ["interleaved-thinking-2025-05-14"] with "invalid beta flag"
Opus 4.7 rejects thinking.type: "enabled" with: "thinking.type.enabled" is not supported for this model. Use "thinking.type.adaptive" and "output_config.effort" to control thinking behavior.

What Should Happen?

Claude Code should detect Opus 4.7 on Bedrock and use the new adaptive thinking API format instead of the deprecated enabled/budget_tokens format.

Error Messages/Logs

ANTHROPIC_LOG=debug output:

headers: {
  "anthropic-beta": "claude-code-20250219,effort-2025-11-24",
}
body: {
  thinking: [Object ...],
  anthropic_beta: [ "interleaved-thinking-2025-05-14" ],
}

API Error: 400
{"type":"error","request_id":"req_...","error":{"type":"invalid_request_error","message":"invalid beta flag"}}

Steps to Reproduce

Configure Claude Code for Bedrock with Opus 4.7:

{
  "env": {
    "CLAUDE_CODE_USE_BEDROCK": "1",
    "AWS_REGION": "us-west-2",
    "ANTHROPIC_MODEL": "us.anthropic.claude-opus-4-7"
  }
}

Start Claude Code: claude
Send any message — immediately fails with "invalid beta flag"

Workarounds attempted (none worked):

CLAUDE_CODE_DISABLE_EXPERIMENTAL_BETAS=1 — does not strip interleaved-thinking-2025-05-14 from the body
Changing effortLevel — no effect on the beta flag in the body

Claude Model

Opus

Is this a regression?

No — Opus 4.7 is a new model released today (April 16, 2026) with breaking API changes

Claude Code Version

2.1.111 (Claude Code)

Platform

AWS Bedrock Commercial

Operating System

macOS

Terminal/Shell

zsh

Additional Information

Model anthropic.claude-opus-4-7 is available and listed via aws bedrock list-foundation-models
Direct API calls via AWS CLI to us.anthropic.claude-opus-4-7 work correctly without beta flags
Opus 4.6 (anthropic.claude-opus-4-6-v1) continues to work fine with Claude Code
The first-party Anthropic API likely handles this correctly since opus alias resolves to 4.7 there; the issue is specific to the Bedrock InvokeModel path

extent analysis

TL;DR

Update Claude Code to use the new adaptive thinking API format for Opus 4.7 on Bedrock, replacing the deprecated enabled/budget_tokens format.

Guidance

Verify that the issue is indeed caused by the breaking change in Opus 4.7 by checking the API request body and ensuring it matches the old format.
Update the Claude Code configuration to use thinking.type: "adaptive" with output_config: {effort: "high"} for Opus 4.7 on Bedrock.
Remove the anthropic_beta flag from the request body, as it is no longer supported by Opus 4.7.
Test the updated configuration to ensure it resolves the "invalid beta flag" error.

Example

{
  "thinking": {
    "type": "adaptive",
    "output_config": {
      "effort": "high"
    }
  }
}

Notes

This fix assumes that the issue is solely caused by the breaking change in Opus 4.7 and that the updated adaptive thinking API format is correctly implemented in Claude Code.

Recommendation

Apply the workaround by updating the Claude Code configuration to use the new adaptive thinking API format for Opus 4.7 on Bedrock, as this is a breaking change introduced by the new model and not a regression in Claude Code.

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claude-code - 💡(How to fix) Fix [BUG] Opus 4.7 on Bedrock fails with 'invalid beta flag' — Claude Code sends deprecated thinking API format [4 comments, 4 participants]

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