gabrielmoreira Lindy Common Errors
Overview
Troubleshooting guide for Lindy AI agent errors. Lindy agents fail at specific points in the workflow: trigger reception, action execution, condition evaluation, or exit condition evaluation. This guide covers each failure class.
Prerequisites
- Access to Lindy dashboard (https://app.lindy.ai)
- Ability to view agent Tasks tab for error details
- For webhook debugging: curl installed
Instructions
- Capture the failing run identifier, trigger payload shape, and first failing step without copying sensitive fields into the incident record.
- Reproduce the behavior in a test agent or disabled workflow using a bounded input.
- Apply the smallest trace-supported remediation, then rerun both the failure fixture and a normal-success fixture before restoring schedules.
Trigger Errors
Webhook Not Firing
Symptoms: No task created when webhook is sent Causes & Solutions:
| Cause | Diagnostic | Fix |
|---|---|---|
| Wrong URL | Check webhook URL in agent config | Copy exact URL from trigger settings |
| Missing auth | curl -v shows 401 |
Add Authorization: Bearer <secret> header |
| Agent inactive | Dashboard shows agent paused | Activate the agent |
| Filter blocking | Trigger filter too restrictive | Review filter conditions, test with broader filter |
| Wrong HTTP method | Using GET instead of POST | Lindy webhooks require POST |
# Diagnostic: Test webhook connectivity
curl -v -X POST "https://public.lindy.ai/api/v1/webhooks/YOUR_ID" \
-H "Authorization: Bearer YOUR_SECRET" \
-H "Content-Type: application/json" \
-d '{"test": true}'
# Expect: 200 OK
Email Trigger Not Activating
Symptoms: Emails arrive but agent does not wake up Solutions:
- Verify Gmail/Outlook authorization is current (re-authorize if expired)
- Check label filter — Lindy Email Received trigger can filter by label
- Confirm email matches trigger filter conditions (sender, subject, etc.)
- Check that agent is active, not paused
Schedule Trigger Missed
Symptoms: Agent did not run at scheduled time Solutions:
- Verify timezone settings match your expectation
- Check credit balance — agents stop if credits exhausted
- Review schedule configuration (daily vs weekday vs custom)
Action Errors
Slack Send Failed
| Error | Cause | Fix |
|---|---|---|
| Channel not found | Channel name wrong or private | Use exact channel name; ensure bot is invited |
| Not authorized | Slack token expired | Re-authorize Slack in Lindy integrations |
| Rate limited | Too many messages | Reduce trigger frequency or batch messages |
Gmail Send Failed
| Error | Cause | Fix |
|---|---|---|
| Authentication expired | OAuth token expired | Re-authorize Gmail in Settings |
| Recipient rejected | Invalid email address | Validate email format in prior step |
| Draft not found | Thread ID mismatch | Verify thread context in action config |
HTTP Request Action Failed
| Error | Cause | Fix |
|---|---|---|
| Connection refused | Target API down | Verify target URL is reachable |
| 401 Unauthorized | Auth header misconfigured | Check Authorization header value |
| Timeout | Target API slow | Increase timeout or optimize target endpoint |
| SSL error | Invalid certificate | Ensure target uses valid HTTPS cert |
# Diagnostic: Test target API independently
curl -v -X POST "https://api.yourapp.com/endpoint" \
-H "Content-Type: application/json" \
-d '{"test": true}'
Run Code Action Failed
| Error | Cause | Fix |
|---|---|---|
| Import error | Library not available | Use only pre-installed libraries (pandas, numpy, etc.) |
| Type error | Input variable is string | Cast explicitly: int(var), json.loads(var) |
| Timeout | Long-running computation | Optimize code; avoid infinite loops |
| Return value empty | No return statement |
Add explicit return with result data |
Knowledge Base Returns No Results
| Cause | Fix |
|---|---|
| Fuzziness at 0 (keyword only) | Increase to 100 for semantic search |
| Content not indexed | Trigger Resync Knowledge Base action |
| Query too vague | Switch field to AI Prompt mode with specific instructions |
| File too large (>20MB) | Split into smaller files |
Agent Step Errors
Agent Loops Indefinitely
Cause: Exit conditions never satisfied Fix: Add measurable, achievable exit conditions:
Primary: "Found at least 3 relevant results"
Fallback: "Made 5 search attempts without finding results"
Agent Picks Wrong Condition Branch
Cause: Ambiguous condition prompt Fix: Make conditions mutually exclusive with clear criteria:
Branch A: "Go down this path if the email mentions billing, payment, or invoice"
Branch B: "Go down this path if the email mentions a technical issue, bug, or error"
Branch C: "Go down this path for all other topics"
Credit Overrun Warning
Symptom: "Task using more resources than expected" pause Cause: Agent step consuming too many credits (complex reasoning) Fix: Simplify prompt, reduce available skills (2-4 max), use smaller model
Debugging Checklist
- Open agent Tasks tab — find the failed task
- Click into the task — review each step's input/output
- Identify the failing step (red indicator)
- Check the step's error message and stack trace
- Verify integration authorizations are current
- Test the trigger independently (curl for webhooks)
- Test the action independently (manual run)
- Check credit balance — insufficient credits halt execution
Error Handling
| Error Category | HTTP Status | Retry? | Notes |
|---|---|---|---|
| Auth failure | 401 | No | Re-authorize integration |
| Rate limited | 429 | Yes | Wait for credit reset |
| Agent not found | 404 | No | Verify agent exists and is active |
| Action timeout | 504 | Yes | Simplify step or increase timeout |
| Run Code error | 500 | Maybe | Fix code, then retry |
| Credit exhausted | 402 | No | Upgrade plan or wait for monthly reset |
Output
Return a compact incident record: observed error, failing trigger or action, correlation ID, reproduction input, remediation applied, and the verification result. Separate platform failures from errors in the connected service.
Examples
When an agent step times out, replay the same bounded input in a test agent, inspect the step trace, reduce the action payload or timeout only where the trace identifies the bottleneck, then rerun the original fixture before re-enabling the production schedule.
Resources
- Lindy Documentation
- Lindy Community
- Lindy Status
Next Steps
Proceed to lindy-debug-bundle for comprehensive diagnostics.