Agent skill · data analytics · jeremylongshore
retellai-common-errors
Diagnose and fix Retell AI voice agent errors: call failures, webhook
Why this skill is useful
Provides specific troubleshooting steps and code snippets for diagnosing and fixing Retell AI errors that the AI wouldn't reliably generate on its own.
What it needs
Requires retell-sdk installed locally. Requires retellai account access. About 2k tokens when loaded. Last updated 2026-08-07. 2,604 stars on the source repository.
What this skill does
Retell AI Common Errors Overview Quick reference for the top Retell AI errors and their solutions. Prerequisites retell-sdk installed API key configured Instructions Error 1: 401 Unauthorized Fix: Verify API key in Retell Dashboard. Ensure RETELLAPIKEY starts with key. Error 2: Call Fails Immediately Fix: Use E.164 format: +14155551234. Both fromnumber and tonumber must be valid. Error 3: Agent Not Responding Fix: Check LLM configuration: Error 4: Function Call Timeout Fix: Your function endpoint must respond within 5 seconds. Offload heavy work: Error 5: Webhook Not Receiving Events Fix: Set webhookurl on the agent, not just in Dashboard settings: Error 6: Voice Quality Issues Fix: Check network latency to Retell servers. Use a voice optimized for your use case. Try different voice IDs. Output Error identified and root cause found Fix applied and verified Call successfully completed Error Handling HTTP Code Meaning Retryable ----------- --------- ----------- 400 Bad request No — fix params 401 Invalid API key No — fix key 404 Agent/call not found No — fix ID 429 Rate limited Yes — backoff 500+ Server error Yes — retry Examples Triage a failed outbound call request When an outbound request returns an error, record the HTTP status, request correlation ID, and the target environment without storing the phone number in the shared incident log. Retry only idempotent requests with bounded backoff; do not retry an ambiguous call-creation response until the provider state is checked. If the error is credential-related, rotate the affected test secret and confirm the replacement against a sandbox agent before resuming traffic. Resources Retell AI Documentation retell-sdk npm Next Steps For debugging, see retellai-debug-bundle.
How to use it
Reference it in AdaL, Claude Code, Cursor or any coding agent — nothing to install:
@skills jeremylongshore/retellai-common-errors--0239df