Table type change; check whether data updates are required

What causes this issue?

The table type has changed from CLUSTER to POOL. For performance
reasons no check was made to see whether the cluster table contained
data.

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?

Find out whether the table contains data. If there is no data in the
table, you can execute the 'Force activation' function. If data does
exist, use the DB utility in the ABAP/4 Dictionary to activate and
convert the table.

Error message extract from SAP system. Copyright SAP SE.