retellai-common-errors
Diagnose and fix Retell AI voice agent errors: call failures, webhook issues, voice quality. Use when encountering Retell AI errors, debugging call issues, or troubleshooting agents. Trigger with phrases like "retell error", "call failed", "voice agent not working", "retell debug".
Best use case
retellai-common-errors is best used when you need a repeatable AI agent workflow instead of a one-off prompt.
Diagnose and fix Retell AI voice agent errors: call failures, webhook issues, voice quality. Use when encountering Retell AI errors, debugging call issues, or troubleshooting agents. Trigger with phrases like "retell error", "call failed", "voice agent not working", "retell debug".
Teams using retellai-common-errors should expect a more consistent output, faster repeated execution, less prompt rewriting.
When to use this skill
- You want a reusable workflow that can be run more than once with consistent structure.
When not to use this skill
- You only need a quick one-off answer and do not need a reusable workflow.
- You cannot install or maintain the underlying files, dependencies, or repository context.
Installation
Claude Code / Cursor / Codex
Manual Installation
- Download SKILL.md from GitHub
- Place it in
.claude/skills/retellai-common-errors/SKILL.mdinside your project - Restart your AI agent — it will auto-discover the skill
How retellai-common-errors Compares
| Feature / Agent | retellai-common-errors | Standard Approach |
|---|---|---|
| Platform Support | Not specified | Limited / Varies |
| Context Awareness | High | Baseline |
| Installation Complexity | Unknown | N/A |
Frequently Asked Questions
What does this skill do?
Diagnose and fix Retell AI voice agent errors: call failures, webhook issues, voice quality. Use when encountering Retell AI errors, debugging call issues, or troubleshooting agents. Trigger with phrases like "retell error", "call failed", "voice agent not working", "retell debug".
Where can I find the source code?
You can find the source code on GitHub using the link provided at the top of the page.
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SKILL.md Source
# 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
```
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:
```typescript
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:
```typescript
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:
```typescript
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
- [Retell AI Documentation](https://docs.retellai.com)
- [retell-sdk npm](https://www.npmjs.com/package/retell-sdk)
## Next Steps
For debugging, see `retellai-debug-bundle`.Related Skills
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