When using the Gurobi Cluster Manager, a user might encounter an Unauthorized access error. This is due to a problem with the method of authentication used to connect to the Cluster Manager.
When using a username and password to authenticate with the Cluster Manager, the user is assigned a temporary web token that is valid for eight hours. After eight hours have elapsed, the user's session with the Cluster Manager will end. As a consequence, if a user begins solving a large model after authenticating with the Cluster Manager via username/password, the solver could suddenly terminate with an Unauthorized access error after eight hours of solving.
API key authentication
For a more secure and reliable way to authenticate with the Cluster Manager, Gurobi strongly recommends using an API key. With this authentication approach, users would encounter Unauthorized access errors if the API key is invalid.