Claude Code exits with code 5 after successful PR review

[tetienne]

Describe the bug

Claude Code Action successfully completes a PR review (posts comments to the PR) but then exits with code 5, causing the GitHub Actions workflow to fail. The review is fully functional - comments are posted - but the non-zero exit code breaks CI pipelines.

To Reproduce

1. Set up a workflow using anthropics/claude-code-action@v1 with AWS Bedrock
2. Trigger a PR review via @claude mention
3. Claude successfully analyzes the PR and posts review comments
4. Action exits with code 5 despite successful execution

Expected behavior

When Claude successfully completes a review and posts comments, the action should exit with code 0.

Screenshots

GitHub Actions log showing the error:

2026-01-20T15:33:16.4373874Z Successfully formatted Claude Code report
...
2026-01-20T15:33:16.7597431Z ##[error]Process completed with exit code 5.

The review was successfully posted (multiple inline comments about SQL injection and N+1 queries were added to the PR).

Workflow yml file

name: Claude PR Review

on:
  issue_comment:
    types: [created]

jobs:
  claude-review:
    if: github.event.issue.pull_request && contains(github.event.comment.body, '@claude')
    runs-on: ubuntu-latest
    permissions:
      contents: read
      pull-requests: write
      issues: write
    steps:
      - uses: actions/checkout@v4

      - uses: anthropics/claude-code-action@v1
        with:
          use_bedrock: 'true'
          prompt: |
            Review this PR for code quality issues.
          claude_args: |
            --model eu.anthropic.claude-sonnet-4-5-20250929-v1:0
            --allowedTools "mcp__github__get_pull_request,mcp__github__get_pull_request_diff,mcp__github__get_pull_request_files,mcp__github__get_pull_request_status,mcp__github__pull_request_read,mcp__github__create_pending_pull_request_review,mcp__github__submit_pending_pull_request_review,mcp__github__pull_request_review_write,mcp__github__add_comment_to_pending_review,mcp__github__add_issue_comment,Bash(gh pr view:*),Bash(gh pr diff:*),Bash(gh api:*),Grep,Read"

API Provider

• Anthropic First-Party API (default)
• AWS Bedrock
• GCP Vertex

Additional context

• Model used: eu.anthropic.claude-sonnet-4-5-20250929-v1:0
• Bun version: 1.2.11

The action clearly succeeded in its task (review comments were posted), but something in the cleanup or finalization phase returns exit code 5. This makes it impossible to use the action in CI pipelines without continue-on-error: true, which defeats the purpose of detecting actual failures.

Exit code 5 doesn't appear to be documented. Is this a known exit code? What does it signify?

[Zal4DW]

I'm experiencing a similar issue with a slightly different error message that might help with debugging.

My Error:

SDK execution error: CLI output was not valid JSON. This may indicate an error during startup. 
Output: {"type":"result","subtype":"success","is_error":false,"duration_ms":209597,"duration_api_ms":209978,"num_turns":22,"result":"Perfect! The review has been posted. Let me provide you with a summary of m...

Key Observations:

1. The action completed successfully (22 turns, "subtype":"success", "is_error":false)
2. The review comment was posted to the PR
3. The SDK then crashed when trying to parse the success result JSON

The error comes from sdk.mjs:7913 in @anthropic-ai/claude-agent-sdk where it's trying to parse streaming JSON output. It appears the result message was truncated or contained characters that broke the JSON parser.

Workaround:
Adding continue-on-error: true to the workflow step allows CI to pass while the review is still posted successfully.

Environment:

• anthropics/claude-code-action@v1 (v1.0.30)
• Claude Code v2.1.9
• @anthropic-ai/claude-agent-sdk@0.2.9
• Model: claude-sonnet-4-5-20250929