Inconsistencies found on the database (&1/&2/&3/&4)

What causes this issue?

Inconsistencies were found when reading from the database. This could
lead to the display of incomplete data in some cases.

System Response

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

How to fix this error?

Execute the reports for checking the class library. Using these results
you can see where the problem lies.

Error message extract from SAP system. Copyright SAP SE.