While using drag and drop to move a task in a timeline I get the following error:
CMN-0015: Attribute 'previous_sibling' was locked and cannot be changed.
How can I unlock this attribute?
There is a process on the task object that as part of a system action locks all attributes, but unlocks just a few.
Use the Unlock All Attributes system action in the process.
The attribute itself is not one of the specific attributes that can be locked or unlocked, but it gets locked or unlocked by the Lock All Attributes or Unlock All Attributes options.
To avoid these scenarios, it is recommended to lock/unlock named attributes that can be found on the system action instead of using the All Attributes option