You have marked more than 255 entries

What causes this issue?

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

System Response

The maximum number of entries that can be selected is 255. Depending on
the database, this can result in a termination.

How to fix this error?

Select fewer lines in the list.

Error message extract from SAP system. Copyright SAP SE.