Problem
When you upgrade to 5.3, the scheduled tasks you created in Manager breaks and the task scheduler log shows something similar to the below.
6/3/2024 7:22:00 AM Importer failed: Missing authentication definition C:\ProgramData\Signifikant\Assert\api-permission-client.config
Location of log is by default C:\ProgramData\Signifikant\Assert\TaskSchedulerLogFiles, but can be changed in the Task Schedule dialogue in Manager application.
Solution
Task scheduler api permissions are configured in a separate file which needs to be created. See this article for file definition.