Index checks returned at least one warning as result

What causes this issue?

The results of the last run of index checks contain at least one
warning.

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?

To check the status, choose the icon in the <ZK>Details</> column to
call the dialog box containing the current results of the last run of
index checks.

Procedure for System Administrators

Error message extract from SAP system. Copyright SAP SE.