Define the function module for the logical directory

What causes this issue?

The option 'logical directory' has been selected and a corresponding
logical directory entered.
Nothing was entered for 'function module'; however, this entry is not
required for creating the path name.

System Response

The entry cannot be saved like this.

How to fix this error?

You must enter a function module as this is required for creating path
names with help of a logical directory. Via the possible entries for
field 'function module', you can select one such function module for
file name generation.

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.