Debugging Common Webhook Issues

Webhooks are powerful, but they can be tricky to debug when things go wrong. Here's how to troubleshoot the most common issues.

1. Webhook Not Being Received

Symptoms: Your endpoint never receives the webhook request.

Possible causes:

• Incorrect URL configuration
• Firewall blocking incoming requests
• DNS issues
• The sending service has an outage

How to debug:

• Use WebhookApp to generate a test URL and verify the sender is working
• Check your server logs for any incoming requests
• Verify your firewall allows incoming HTTP/HTTPS traffic

2. Receiving 4xx Errors

Common 4xx errors:

• 400 Bad Request - Your server can't parse the request
• 401 Unauthorized - Missing or invalid authentication
• 403 Forbidden - Your server is rejecting the request
• 404 Not Found - Wrong endpoint URL

Solutions:

• Log the raw request body before parsing
• Check your authentication middleware
• Verify the exact URL path matches your route

3. Timeout Errors

Most webhook senders expect a response within 5-30 seconds.

Best practices:

• Return 200 immediately, then process asynchronously
• Use a message queue for heavy processing
• Avoid making slow external API calls in the webhook handler

4. Duplicate Webhooks

Many services implement at-least-once delivery, meaning you might receive the same webhook multiple times.

How to handle:

• Store processed webhook IDs
• Use idempotency keys
• Check timestamps to ignore old duplicates

5. Invalid Signatures

When signature verification fails:

• Ensure you're using the raw request body (not parsed JSON)
• Check that you're using the correct secret key
• Verify the signature algorithm matches the documentation

Pro Tip: Use WebhookApp for Debugging

WebhookApp captures every detail of incoming requests:

• Full headers
• Request body
• Query parameters
• Source IP address
• Timestamp

This makes it invaluable for debugging webhook integrations!