Troubleshooting Common API Errors

403 Forbidden Errors

Cause: Invalid or expired API credentials, insufficient permissions, or wrong environment.

Solutions:

• Verify your API key and secret are correct
• Check if your OAuth token has expired and refresh it
• Ensure you're using the correct environment (sandbox vs production)
• Confirm your account has been enabled for API access

Authentication Failures

Cause: Incorrect OAuth flow, expired tokens, or malformed requests.

Solutions:

• Follow the OAuth 2.0 flow exactly as documented
• Implement automatic token refresh before expiry
• Check that the Authorization header format is correct: Bearer <token>
• Verify your client credentials are for the correct environment

Validation Errors

Cause: Missing required fields, incorrect data formats, or invalid values.

Solutions:

• Check all required fields in the invoice schema are populated
• Verify TIN numbers are valid and correctly formatted
• Ensure HSN codes are from the approved list
• Validate VAT calculations match the expected rates

Sandbox vs Production Issues

Cause: Using sandbox credentials in production or vice versa.

Solutions:

• Use separate configuration for sandbox and production
• Never mix credentials between environments
• Test thoroughly in sandbox before switching to production
• Check the API base URL matches the intended environment