Characteristic &1 is not permitted as a planning characteristic

What causes this issue?

As planning characteristics, you can use all characteristics which can
also be used in a planning layout. These are:
All characteristics which are not marked as 'summarized' in the segment
level characteristics.
In costing based Profitability Analysis, you can also use the
characteristics 'plan/actual indicator', 'currency type', 'transaction
type', 'version', 'period/year' and (if the second period type is
active) 'week/year'.
In account-based Profitability Analysis, you can also use the
characteristics 'plan/actual indicator', 'version', 'cost element' and
'period/year'.

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?

Only include permitted characteristics in the planning level.

Procedure for System Administrators

Error message extract from SAP system. Copyright SAP SE.