Error patterns (compact)
Use this to quickly map log signatures to likely causes and fixes.
| Log pattern | Likely cause | Quick fix |
|---|---|---|
KeyError, not defined, missing environment | Missing env var | Add env var in render.yaml or via MCP, then redeploy |
EADDRINUSE, listen EADDRINUSE | Port binding conflict | Bind to 0.0.0.0:$PORT |
Cannot find module, ModuleNotFoundError | Missing dependency | Add dependency to manifest and rebuild |
ECONNREFUSED, connection refused | DB not reachable | Verify DATABASE_URL and DB status |
Health check timeout | No healthy response | Add/verify health endpoint and port |
exit 137, out of memory | OOM | Reduce memory use or upgrade plan |
Command failed, build failed | Bad build command | Fix build command or dependencies |