Claude Code exits with code 1 after starting successfully - no actual work completed

[julien51]

Description

Claude Code GitHub Action consistently exits with code 1 after starting successfully. Claude responds to @claude mentions and posts comments, but every run fails with "Claude Code process exited with code 1" after ~300-400ms of execution, regardless of task complexity.

Environment

• Action version: anthropics/claude-code-action@v1
• Claude Code version: 2.0.74 (installed by action)
• Runner: ubuntu-latest
• Authentication: anthropic_api_key (API key from console.anthropic.com)
• Repository type: Yarn workspaces monorepo with Astro builds

Workflow Configuration

Simplified workflow based on official example:

name: Claude Code (Simple)

on:
  issue_comment:
    types: [created]
  pull_request_review_comment:
    types: [created]
  issues:
    types: [opened, assigned]
  pull_request_review:
    types: [submitted]

jobs:
  claude:
    if: |
      (github.event_name == 'issue_comment' && contains(github.event.comment.body, '@claude')) ||
      (github.event_name == 'pull_request_review_comment' && contains(github.event.comment.body, '@claude')) ||
      (github.event_name == 'pull_request_review' && contains(github.event.review.body, '@claude')) ||
      (github.event_name == 'issues' && (contains(github.event.issue.body, '@claude') || contains(github.event.issue.title, '@claude')))
    runs-on: ubuntu-latest
    permissions:
      contents: write
      pull-requests: write
      issues: write
      id-token: write
      actions: read
    steps:
      - name: Checkout repository
        uses: actions/checkout@v5
        with:
          fetch-depth: 0

      - name: Run Claude Code
        uses: anthropics/claude-code-action@v1
        with:
          anthropic_api_key: ${{ secrets.ANTHROPIC_API_KEY }}

Expected Behavior

Claude should process the task and either:

• Complete the task successfully
• Provide a meaningful error message if it cannot complete the task
• Exit with code 0 on success

Actual Behavior

Every single run:

1. ✅ Claude Code installs successfully
2. ✅ Authentication validates
3. ✅ Claude creates a branch (e.g., claude/issue-48-20251228-2345)
4. ✅ Claude posts a comment: "Claude encountered an error —— I'll analyze this and get back to you."
5. ❌ Exits with code 1 after ~300-400ms
6. ❌ Never completes any actual work

Logs

Key excerpts from workflow run:

SDK options: {
  "systemPrompt": {
    "type": "preset",
    "preset": "claude_code"
  },
  "pathToClaudeCodeExecutable": "",
  "extraArgs": {
    "auto-approve": null
  },
  "settingSources": [
    "user",
    "project",
    "local"
  ]
}

[~2 seconds later]

SDK execution error: 13243 |       throw error;
13244 |     }
13245 |   }
13246 |   getProcessExitError(code, signal) {
13247 |     if (code !== 0 && code !== null) {
13248 |       return new Error(`Claude Code process exited with code ${code}`);
                     ^
error: Claude Code process exited with code 1
      at getProcessExitError (/home/runner/work/_actions/anthropics/claude-code-action/v1/base-action/node_modules/@anthropic-ai/claude-agent-sdk/sdk.mjs:13248:14)
      at exitHandler (/home/runner/work/_actions/anthropics/claude-code-action/v1/base-action/node_modules/@anthropic-ai/claude-agent-sdk/sdk.mjs:13373:28)

Statistics from run:

{
  "duration_ms": 338,
  "num_turns": 1,
  "total_cost_usd": 0,
  "permission_denials": []
}

Note: Even with show_full_output: true enabled, no actual Claude Code stderr/stdout is shown in the logs between "SDK options" and "SDK execution error".

Steps to Reproduce

1. Set up workflow with configuration above
2. Add valid ANTHROPIC_API_KEY to repository secrets
3. Comment @claude <any task> on an issue
4. Observe workflow run fails with exit code 1

Tested with various tasks:

• Simple questions: "@claude please explain what this issue is asking for"
• File creation: "@claude please create a simple README.md file"
• Complex tasks: Original issue requesting domain linking analysis

All fail identically.

What We've Tried

Authentication Methods

• ❌ claude_code_oauth_token parameter (validation error)
• ❌ ANTHROPIC_API_KEY env var at job level (validation error)
• ❌ CLAUDE_CODE_OAUTH_TOKEN env var at step level (empty)
• ❌ CLAUDE_CODE_OAUTH_TOKEN env var at job level (empty)
• ✅ anthropic_api_key input parameter (works, but exits with code 1)

Configuration Changes

• Switched from custom OAuth token to API key
• Simplified workflow to match official example exactly
• Removed all custom Node.js/yarn setup steps
• Regenerated API credentials
• Tested on fresh issues

Debugging

• Enabled show_full_output: true - no additional output shown
• Checked for API authentication errors - none found
• Tested with simple and complex tasks - all fail identically

Additional Context

The action is technically "working" in that:

• Authentication succeeds
• Claude responds to mentions
• Branches are created
• Comments are posted

But it never completes any actual work due to the immediate exit code 1.

The $0 cost in the statistics suggests Claude might not be making API calls successfully, or the run is too short to register cost.

Questions

1. Is there a way to see the actual Claude Code CLI stdout/stderr even with show_full_output: true?
2. Are there any known issues with exit code 1 in GitHub Actions environments?
3. Should the action be logging more details about why Claude Code exited?

Related Issues

Similar "exit code 1" errors reported in other contexts:

• v1: App token exchange failed #522 (App token exchange failed)
• Workflow fails on first-time setup but error message says 'this is normal, ignore it' #722 (First-time setup workflow failures)

However, those are different scenarios - our issue occurs on every run, not just first-time setup.

[stevethomas]

I'm seeing the exact same problem. Workflows that were working last week are now failing with exit code 1.

I've tried minimal prompts, cycling the api key, removed MCPs - no improvement.

[mavam]

Another data point with the same symptoms:

Run: https://github.com/tenzir/docs/actions/runs/20594387956/job/59145865759

Trigger: @claude address the review comments on a PR with 2 review comments

Logs show:

{
  "type": "result",
  "subtype": "success",
  "is_error": true,
  "duration_ms": 354,
  "num_turns": 1,
  "total_cost_usd": 0,
  "permission_denials": []
}

Same behavior:

• Claude Code initialized successfully with model claude-sonnet-4-5-20250929
• Exited with code 1 after 354ms
• $0 cost indicates no API call was made
• No actual error message from Claude Code is surfaced

Configuration: Using plugins from a custom marketplace (tenzir/claude-plugins), but the failure happens before any meaningful work.

The key issue is that the SDK's getProcessExitError() only reports the exit code without capturing Claude Code's actual stderr/stdout, making diagnosis impossible.