I am using the validation station in action center. Sending a ocr document to action center for validation, but getting this error. It was working fine earlier.
The remote server returned an error: (403) Forbidden.
The error “The remote server returned an error: (403) Forbidden” typically indicates an issue with authentication or permissions when your UiPath process tries to interact with the Action Center.
Ensure that the user or robot executing the process has the necessary permissions in Orchestrator to access Action Center. This includes permissions to create and manage tasks.
Go to Orchestrator > Tenant > Manage Access > Roles.
Ensure the roles assigned to your user or robot include permissions for Action Center.
Thanks,
Ashok 
As per error it is an authorization issue
Make sure the required actions access is there for the robot you are using…also if using storage account need to have access to that also
cheers