Revenue element & cannot be planned on cost center &

What causes this issue?

The cost center &V2& to be planned is blocked against revenue planning.
The block was made in the master record of this cost center for
period(s) &V3&.

How to fix this error?

Do not plan the cost center/revenue element combination
&V2&/&V1&, or
Shorten the planning period so that cost center &V2& is open for
revenue planning in the new period, or
Arrange for the block to be removed.

Error message extract from SAP system. Copyright SAP SE.