Variable key for main condition record missing

What causes this issue?

The system was unable to find the main condition record belonging to
the period condition record.

System Response

The system determines the following data:
The period condition record has the (internal) number &V1& for
condition type &V2&, area of validity &V3&.
The error occurred in function module &V4&.

How to fix this error?

Contact your system administrator.

Procedure for System Administrators

The problem may be caused by one of the following:
faulty call of function module &V4& with invalid or inconsistent data
database error (i.e. the variable key does not exist in the database
table (VAKE)

Error message extract from SAP system. Copyright SAP SE.