HTTP 401 Unauthorized When Calling Marketplace API via Postman

[sourav_9]

Hi everyone,

I'm troubleshooting an issue where a user is receiving an HTTP 401 Unauthorized response when calling a ServiceNow Marketplace-related API through Postman using Bearer token authentication.

The Authorization header appears to be configured correctly, and the user is supplying a Bearer token, but the request is still being rejected with a 401 response.

What are the most common causes of this issue? In particular, I'm interested in understanding whether it is typically related to:

• An expired or invalid access token

• Incorrect OAuth configuration

• Missing scopes or permissions

• Incorrect endpoint or environment

• Any other common authentication-related issues

Are there specific checks or logs that you would recommend reviewing first when investigating this type of error?

Thank you.

[Tanushree Maiti]

Hi @sourav_9 

• Ensure there is a single space separating the word Bearer and the token value (like Authorization: Bearer <token>)

• Confirm that the generated Bearer token has not expired. 

• Ensure your Postman request uses https:// instead of http://.  ServiceNow strictly rejects unencrypted inbound API authentication requests.

• Ensure the Web Service Access Only field is checked on their user profile to bypass interactive login constraints
• If your instance utilizes Single Sign-On (SSO), ensure the integration user has a valid local ServiceNow password and is configured as an internal integration user

• The integration user must possess the snc_platform_rest_api_access role to access any inbound REST endpoints.

• If your organization uses REST API Access Policies, verify that the active policy is not blocking inbound OAuth requests or requiring specific IP ranges .Refer: : KB1963039 API accounts getting 401 unauthorized error