retellai-common-errors
Troubleshoot common Retell AI issues like 401 unauthorized errors, call timeouts, and voice agent configuration.
Install
mkdir -p .claude/skills/retellai-common-errors && curl -L -o skill.zip "https://agentskills.codes/api/skills/download/9128" && unzip -o skill.zip -d .claude/skills/retellai-common-errors && rm skill.zipInstalls to .claude/skills/retellai-common-errors
Activation
This is the description your AI agent reads to decide when to run this skill — the better it matches your request, the more reliably it fires.
Diagnose and fix Retell AI voice agent errors: call failures, webhookKey capabilities
- →Diagnose 401 unauthorized API errors
- →Validate phone number formats
- →Troubleshoot function call timeouts
- →Verify webhook event reception
- →Debug voice quality and agent responsiveness
How it works
It maps common HTTP error codes and call behaviors to specific configuration fixes, such as updating webhook URLs or adjusting function execution time.
Inputs & outputs
When to use retellai-common-errors
- →Fix 401 unauthorized errors
- →Debug failed phone calls
- →Troubleshoot function call timeouts
- →Verify voice agent LLM prompts
About this skill
Retell AI Common Errors
Overview
Quick reference for the top Retell AI errors and their solutions.
Prerequisites
retell-sdkinstalled- API key configured
Instructions
Error 1: 401 Unauthorized
RetellError: 401 — Invalid API key
Fix: Verify API key in Retell Dashboard. Ensure RETELL_API_KEY starts with key_.
Error 2: Call Fails Immediately
RetellError: 400 — Invalid phone number format
Fix: Use E.164 format: +14155551234. Both from_number and to_number must be valid.
Error 3: Agent Not Responding
Call connected but agent says nothing
Fix: Check LLM configuration:
const llm = await retell.llm.retrieve(agent.response_engine.llm_id);
console.log(`Model: ${llm.model}`);
console.log(`Prompt length: ${llm.general_prompt.length} chars`);
// Ensure general_prompt is not empty and gives clear instructions
Error 4: Function Call Timeout
Function call to https://your-api.com/endpoint timed out
Fix: Your function endpoint must respond within 5 seconds. Offload heavy work:
app.post('/functions/lookup', async (req, res) => {
// Respond immediately with acknowledgment
const result = await quickLookup(req.body.args);
res.json({ result: `Found: ${result.name}` });
// Do NOT run async work before responding
});
Error 5: Webhook Not Receiving Events
No webhook events received after call
Fix: Set webhook_url on the agent, not just in Dashboard settings:
await retell.agent.update(agentId, {
webhook_url: 'https://your-app.com/webhooks/retell',
});
Error 6: Voice Quality Issues
Agent voice sounds robotic/choppy
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 |
Resources
Next Steps
For debugging, see retellai-debug-bundle.
When not to use it
- →When attempting to debug issues outside of the Retell AI platform
Prerequisites
Limitations
- →Function endpoints must respond within 5 seconds
How it compares
This provides a curated list of platform-specific error resolutions rather than generic API debugging steps.
Compared to similar skills
retellai-common-errors side by side with the closest alternatives in the catalog.
| Skill | Installs | Updated | Safety | Difficulty |
|---|---|---|---|---|
| retellai-common-errors (this skill) | 0 | 25d | Review | Intermediate |
| godot | 1,044 | 5mo | Review | Intermediate |
| python-testing-patterns | 77 | 2mo | Review | Intermediate |
| error-handling-patterns | 35 | 2mo | No flags | Intermediate |
Try saying
Example prompts that trigger this skill in your AI assistant.
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