There is still one open planning run

What causes this issue?

Only one open daily package run can exist in reservation planning
(daily package creation or daily package release). As an incomplete
daily package run currently exists in the system, no other runs are
possible.

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?

Wait until the current daily package run (daily package creation or
daily package release) has been completed. Check the log in the
process monitor to see whether errors have occurred and correct them,
if necessary. Then execute the consistency check for mass
processes (transaction /SAPAPO/RSP_CONSIS) to remove the lock and
restart the transaction.

Procedure for System Administrators

Error message extract from SAP system. Copyright SAP SE.