Check T006A and setup of tables T006B and T006C completed

What causes this issue?

The consistency check and cleaning up of the tables T006B and T006C
was cancelled.
An inconsistent state of the table T006C can cause problems
in the units of measurement maintenance transaction, because it carries
out various consistency checks.

System Response

The contents of the table T006A were first tested and corrected as
necessary.
Then the contents of the table T006C were first deleted, and
then reconstructed from the data in the table T006A.
The consistency of the data is thus guaranteed.

How to fix this error?

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.