You may find yourself unable to edit layers or publish images.  These tasks fail in the App Layering Management Console with a cryptic message, "The given key was not present in the dictionary."

First, reboot the ELM.  That may resolve this issue.

If a reboot does not resolve this issue, open the Tasks bar, Show Hidden Tasks, and see what you've got.  Allow any running tasks to complete, and don't start any more.  Once your normal tasks have finished, cancel any stalled tasks.  Once the task list is completely empty, retry the operation.

In this case, the message is actually trying to tell us that there is an entry in the tasks list without an active process, and it needs to be canceled before other tasks can continue.