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Cannot Change Status on Task or Issue

Problem

Users (Including system administrators) cannot change the status of some tasks or issues.

Solution

There are two possible solutions to this issue:

1. The task has children tasks that will not allow its parent to change as long as the child tasks are still open.

2. The task/issue has a resolving object which would prohibit its ability to be changed.  The resolving object can be seen by editing the issue/task.  The field is usually at the bottom of the Overview section of the object.