When using the Gurobi Cluster Manager, you might receive the error "Unauthorized access". This error indicates that there is a problem with the method of authentication used to connect to the Cluster Manager.
Node registration
You may observe the following warning in the logs: warn : Manager registration failed, will retry...: Unauthorized access. This shows the Compute Server (CS) node is not able to authenticate to the Cluster Manager while registering. Please note this uses the cluster token, which is a property in the configulation file. All the CS nodes and Cluster Managers must have the same value. For more information, kindly refer to the section Connecting Nodes of our Reference Manual for Gurobi Remote Services.
Username/password authentication
When using a username and password to authenticate with the Cluster Manager, a temporary web token that is valid for eight hours is assigned to the user. After eight hours have elapsed, the Cluster Manager session will end and the solver could suddenly terminate with an Unauthorized access error.
API key authentication
For a more secure and reliable way to authenticate with the Cluster Manager, Gurobi highly recommends using an API key. With this authentication approach, an Unauthorized access error indicates that the API key is invalid.
Further information