What this error means

ANTHROPIC_API_KEY is not set — web container missing environment variable in Docker Compose is a Docker failure pattern reported for developers trying to fix anthropic_api_key not set error in docker compose web container. Based on the imported evidence, treat this as a tool-specific troubleshooting page rather than a generic API error.

Why this happens

PR #199 (May 2026) fixes a Docker Compose issue where the web service's environment block didn't forward ANTHROPIC_API_KEY from the host. The web container had no Anthropic key, causing all LLM calls to fail with 'ANTHROPIC_API_KEY is not set'. Surfaced during May 11 smoke test.

Common causes

  • Developers running LLM-integrated applications in Docker Compose find that the web container fails with 'ANTHROPIC_API_KEY is not set' even though the host has the variable configured. The docker-compose.yml environment block doesn't forward ANTHROPIC_API_KEY from the host, causing all LLM calls (prep brief, clinical analysis, protocol generation) to fail silently.
  • PR #199 (May 2026) fixes a Docker Compose issue where the web service's environment block didn't forward ANTHROPIC_API_KEY from the host. The web container had no Anthropic key, causing all LLM calls to fail with 'ANTHROPIC_API_KEY is not set'. Surfaced during May 11 smoke test.

Quick fixes

  1. Confirm the exact error signature matches ANTHROPIC_API_KEY is not set — web container missing environment variable in Docker Compose.
  2. Check the Docker account, local tool state, and provider configuration involved in the failing workflow.
  3. Compare the failing environment with a known working setup, then change one configuration value at a time.

Platform/tool-specific checks

  • Verify the command, editor, extension, or API client that produced the error.
  • Compare local settings with CI, deployment, or editor-level settings when the error appears in only one environment.
  • Avoid deleting credentials, local model data, or project settings until the failing scope is clear.

Step-by-step troubleshooting

  1. Capture the exact error message and the command, editor action, or request that triggered it.
  2. Check whether the failure is account/auth, quota/rate, model/provider, local runtime, or deployment configuration.
  3. Review the source evidence below and compare it with your environment.
  4. Apply one change at a time and rerun the smallest failing action.
  5. Keep the working fix documented for the team or deployment environment.

How to prevent it

  • Keep provider/tool configuration documented.
  • Record non-secret diagnostics such as tool version, provider name, model name, and command path.
  • Add a lightweight check before CI or production workflows depend on the tool.