One or more maintenance items do not have packages assigned to them yet

What causes this issue?

The task list contains one or more maintenance items that do not have a
package assigned to them.

How to fix this error?

Change the task list so that all the maintenance items have a
maintenance package assigned to them.

Procedure for System Administrators

It was configured in Customizing that this message should be issued.

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

If you want to use task lists without package assignments, you need to
modify the message type for this message in Customizing. You can modify
the message type in the Customizing activity Message Control under
'Maintenance and Service Orders'.
If you do not make any changes, message type 'I' is used.
Message types 'E', 'X', and 'P' are interpreted as message type 'E'.
Message types 'I', 'S', and 'W' are interpreted accordingly.
If the message type is 'initial', it is still possible to do the
following without having a message appear: You can save task lists that
have items without package assignments. You can include items without
package assignments in a task list that already has at least one item
with a package assignment. Otherwise, message IP364 is issued, just as
usual.

Error message extract from SAP system. Copyright SAP SE.