---

name: customerio-common-errors description: | Diagnose and fix Customer.io common errors. Use when troubleshooting API errors, delivery issues, or integration problems with Customer.io. Trigger with phrases like "customer.io error", "customer.io not working", "debug customer.io", "customer.io issue". allowed-tools: Read, Grep, Bash(curl:*) version: 1.0.0 license: MIT author: Jeremy Longshore jeremy@intentsolutions.io

Customer.io Common Errors

Overview

Diagnose and resolve common Customer.io integration errors, delivery issues, and API problems.

Error Categories

Authentication Errors

Error: 401 Unauthorized

Copy{
  "meta": {
    "error": "Unauthorized"
  }
}

Cause: Invalid Site ID or API Key Solution:

1. Verify credentials in Customer.io Settings > API Credentials
2. Check you're using Track API key (not App API key) for identify/track
3. Ensure environment variables are loaded correctly

Copy# Verify environment variables
echo "Site ID: ${CUSTOMERIO_SITE_ID:0:8}..."
echo "API Key: ${CUSTOMERIO_API_KEY:0:8}..."

Error: 403 Forbidden

Cause: API key doesn't have required permissions Solution: Generate new API key with correct scope (Track vs App API)

Request Errors

Error: 400 Bad Request - Invalid identifier

Copy{
  "meta": {
    "error": "identifier is required"
  }
}

Cause: Missing or empty user ID Solution:

Copy// Wrong
await client.identify('', { email: 'user@example.com' });

// Correct
await client.identify('user-123', { email: 'user@example.com' });

Error: 400 Bad Request - Invalid timestamp

Copy{
  "meta": {
    "error": "timestamp must be a valid unix timestamp"
  }
}

Cause: Using milliseconds instead of seconds Solution:

Copy// Wrong
{ created_at: Date.now() } // 1704067200000

// Correct
{ created_at: Math.floor(Date.now() / 1000) } // 1704067200

Error: 400 Bad Request - Invalid email

Cause: Malformed email address Solution:

Copy// Validate email before sending
const emailRegex = /^[^\s@]+@[^\s@]+\.[^\s@]+$/;
if (!emailRegex.test(email)) {
  throw new Error('Invalid email format');
}

Rate Limiting

Error: 429 Too Many Requests

Copy{
  "meta": {
    "error": "Rate limit exceeded"
  }
}

Cause: Exceeded API rate limits Solution:

Copy// Implement exponential backoff
async function withBackoff(fn: () => Promise<any>, maxRetries = 3) {
  for (let i = 0; i < maxRetries; i++) {
    try {
      return await fn();
    } catch (error: any) {
      if (error.status === 429 && i < maxRetries - 1) {
        const delay = Math.pow(2, i) * 1000;
        await new Promise(r => setTimeout(r, delay));
        continue;
      }
      throw error;
    }
  }
}

Delivery Issues

Issue: Email not delivered

Diagnostic steps:

1. Check People > User > Activity for event receipt
2. Verify campaign is active and user matches segment
3. Check Deliverability > Suppression list
4. Review message preview for errors

Copy# Check user exists via API
curl -X GET "https://track.customer.io/api/v1/customers/user-123" \
  -u "$CUSTOMERIO_SITE_ID:$CUSTOMERIO_API_KEY"

Issue: Event not triggering campaign

Cause: Event name mismatch or missing attributes Solution:

Copy// Check exact event name in dashboard
// Event names are case-sensitive
await client.track(userId, {
  name: 'signed_up',  // Must match exactly
  data: { source: 'web' }
});

Issue: User not in segment

Cause: Missing or incorrect attributes Solution:

1. Check segment conditions in dashboard
2. Verify user has required attributes
3. Check attribute types match (string vs number)

SDK-Specific Errors

Node.js: TypeError - Cannot read property

Copy// Wrong - SDK not initialized
const client = new TrackClient(undefined, undefined);

// Correct - Check env vars exist
if (!process.env.CUSTOMERIO_SITE_ID) {
  throw new Error('CUSTOMERIO_SITE_ID not set');
}

Python: ConnectionError

Copy# Handle network errors
import customerio
from customerio.errors import CustomerIOError

try:
    cio.identify(id='user-123', email='user@example.com')
except CustomerIOError as e:
    print(f"Customer.io error: {e}")
except ConnectionError as e:
    print(f"Network error: {e}")

Diagnostic Commands

Check API Connectivity

Copycurl -X POST "https://track.customer.io/api/v1/customers/test-user" \
  -u "$CUSTOMERIO_SITE_ID:$CUSTOMERIO_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"email":"test@example.com"}' \
  -w "\nHTTP Status: %{http_code}\n"

Verify Event Delivery

Copycurl -X POST "https://track.customer.io/api/v1/customers/test-user/events" \
  -u "$CUSTOMERIO_SITE_ID:$CUSTOMERIO_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"name":"test_event","data":{"test":true}}'

Error Handling

Resources

• API Error Reference
• Troubleshooting Guide
• Status Page

Next Steps

After resolving errors, proceed to customerio-debug-bundle to create comprehensive debug reports.