When auto-numbering is enabled for the ID attribute of the Task object, all Task ID fields become non-modifiable.
In order to make an edit to the ID of a task when auto-numbering is enabled, take these steps
- Navigate to Administration > Objects > Task > Attributes tab
- Click on the 'ID' attribute
- Click on the 'Auto-numbering' tab
- Uncheck the 'Auto-numbered' checkbox
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- Save and Return
After that, you can make any necessary changes to your task ID's. Once that is done, be sure to re-enable the auto-numbering functionality so new created tasks are auto-numbered.