Check T006A and setup of tables T006B and T006C started

What causes this issue?

The consistency of the tables T006A and T006C is checked, and they are
cleaned up.
An inconsistent status of table T006C can cause problems in the
measurement unit maintenance transaction, as it carries out several
consistency checks.

System Response

The contents of table T006A (language-dependent keys for measurement
units) are checked and corrected first.
Then the contents of table T006C are deleted and rebuilt from the data
in table T006A.
This ensures the consistency of the dataset.

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.