Open items in migration plan &1 cannot be reset

What causes this issue?

Errors occurred while resetting the open items. The log lists which
errors occurred. Due to the error messages that were issued, it is <ZH>
not</> possible to reset the open items in the other migration plans.
See the long texts for the messages <DS:NA.FAGL_MIG305>FAGL_MIG 305</>
and <DS:NA.FAGL_MIG306>FAGL_MIG 306</>.

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?

Open items that have already been migrated in migration plans with a
more recent migration date do <ZH>not</> contain the detailed document
splitting information.
As a precaution, we recommend resetting the open items of migration plan
&V1& and migrating them again.

Procedure for System Administrators

Error message extract from SAP system. Copyright SAP SE.