PSA table &1: Non-unique index does not exist, but is defined in metadata

What causes this issue?

You have defined a non-unique index for a column-organized PSA table. At
the point in time when the index was created, non-unique indexes were
not supported. The index was therefore not created in the database.

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?

For more information about how to proceed, see SAP Note 2555566.

Procedure for System Administrators

Error message extract from SAP system. Copyright SAP SE.