When trying to generate a user API authentication token in TMS you receive an error code 100 "Authentication failed"  in the Response Body.

{
  "Error": {
    "Code": 100,
    "Description": "Authentication failed."
  }
}

Resolution
1. Verify the user has the correct group membership if used.
2. Test user credentials by login to TMS. If login fails, check whether the user account is active, reset the password, and verify username is correct
3. Change the user account password

 

1. Expired password
2. Incorrect group membership
3. Incorrect username or password
4. TMS has limitation to have Rest API token generated if the password length is more than 15 character.