Customizing error in work schedule rule & & & &

What causes this issue?

There are no valid system entries for the displayed work schedule rule.
This is a customizing error. Possible causes are inconsistencies in
tables T508A, T508Z, T550A, T550P, T551A, T551C, and T553A, or work
schedules that have not been generated.

System Response

Processing of the time data is cancelled.

How to fix this error?

The error message parameters are sorted as follows:
Employee subgroup grouping
Public holiday calendar
Personnel area grouping
Work schedule rule
This data should help you to find and correct the inconsistencies more
quickly. You can then restart the program.

Error message extract from SAP system. Copyright SAP SE.