If you have already logged in but see the LOGIN REQUIRED ACB_ERROR_CODE.10 when calling another API function you may not be managing the sessions properly. 

All API calling users have to create a routine for session invalidation. 

Below are cases where sessions are invalid: 

1. A new login is made every time because the API is misused.

2. The server is restarted often.

3. Cookie value is not refreshed or not updated. 

4. A session timeout happens.