Set name might become too long

What causes this issue?

If you enter a grouping field for automatic set generation, then the
system groups those objects that have the same value in this grouping
field into sets. The set name is created based on the pattern you enter
in the <ZK>Set Name </>field, whereby the placeholder (%) is replaced
with the value entered in the grouping field.
Your entries can cause the set name that results to be too long. This
happens if the length of the entry in the grouping field is longer than
the number of characters still free in the pattern for the set name.

System Response

In certain cases the system cuts off the set name. As a result, the set
name might <ZH>not </>be unique any longer.

How to fix this error?

Check the pattern for the set name. Whether or not the set name will
really be too long depends on the actual field contents.

Procedure for System Administrators

The system issues an error message and will not allow you to continue with this transaction until the error is resolved.

Error message extract from SAP system. Copyright SAP SE.