Unknown period type (&)

What causes this issue?

When reading the statistical data from the database, an invalid value
was specified for the period type. Valid period types are <LS>day</>,
<LS>week</>, and <LS>month</>.

System Response

The system cannot read the requested data.

How to fix this error?

Restart the workload monitor.

Procedure for System Administrators

The system issues an error message and will not allow you to continue with this transaction until the error is resolved.

Error message extract from SAP system. Copyright SAP SE.