1. Cannot create inbound REST module     

• Missing required fields: Ensure Name, Base URI, and Authentication Type are provided.
  
• Duplicate base URI: Use a unique base URI for each module.
• Invalid base URI format: The base URI should begin with a / and contain no spaces or special characters.
  

2. API endpoint not getting triggered     

• Incorrect endpoint path: Verify that the final URL includes the correct base URI and endpoint path.
• Function or Circuit not linked: Ensure a valid resource is selected.

3. Validation error: Request not processed

• Missing mandatory parameters: Ensure all required parameters are included in the request.
  
• Incorrect parameter format: Match the data types (e.g., number, text) and allowed values.
• Regex or length mismatch: Input may not meet defined pattern or length constraints.
  

4. Request body issues     

• Wrong body type selected: Choose the correct body format—Raw, x-www-form-urlencoded, or None.
• File upload not working: File uploads are only supported with Function resources, not Circuits.
• Min/Max length not satisfied: Ensure the body content respects the length validation rules if set.

5. Authentication failures     

• Invalid OAuth token: Make sure the token is valid and includes the correct scopes.
• Incorrect API key: Check if the API key provided matches the one set in Qntrl.
• Missing authorization header: Ensure the required authentication headers are passed correctly.

6. Rate limit errors     

• Too many requests (429 Error): The request rate has exceeded the defined limit.
• Wrong policy attached: Confirm the correct rate limit policy is selected.
• Per-IP not working as expected: Review whether the Per-IP option is enabled as needed.

7. Function/Circuit error debugging  

• Check Script Logs – Review the logs for any errors or issues in the script execution.
• Review Circuit Execution Logs – Look into the circuit execution logs for step-by-step insights into where the error occurred.

• Use Postman, CURL or Qntrl's Outbound REST Web Service to test the endpoint during development.
• If using OAuth, ensure the correct scope is set and token is valid.
• Always test each endpoint before publishing.