If you encounter an error when trying to close a task linked to a maintenance plan, the cause depends on the type of plan the task belongs to.
Fixed-date maintenance plan
In a fixed-date plan, tasks must be closed in chronological order based on their scheduled date.
Rule: A task cannot be closed if a previous task (with an earlier scheduled date) is still active.
Example: If a task scheduled for 09/15 is still open, you cannot close the task scheduled for 10/15.
Solution: Close the oldest tasks first, in order of their scheduled dates.
Task-closure maintenance plan
In this type of plan, two tasks from the same plan cannot be closed on the same day.
Rule: The closure date of a task must be different from that of any other task already closed in the same plan.
Example: If you try to close a task with the date 03/02/2026 and another task in the same plan was already closed on that date, the system will display an error: "The recurrence date 2026-03-02 is already used".
Solution: Change the closure date or the last activity date so that it differs from the one already used in the plan.
Counter-based maintenance plan
In this type of plan, tasks are automatically generated when a counter reading reaches or exceeds a defined threshold. Closing a task does not depend on a date rule, but the task must exist before it can be closed.
If you cannot find a task to close, check that the counter reading has reached the threshold configured in the plan.