This message typically indicates a temporary disconnection between the database and the TapRooT® Software. As a safety measure, the document you had open at the time stays locked to keep other users from accidentally overwriting your work. Now it's just waiting to be told that it's OK to let that document be edited again.
To clear the locked SnapCharT, click on the Admin tab at the top and scroll to the bottom of that page. Depending on the TapRooT® Software that you are running, you can see either the option "Clear Cache & Locks" or, in the bottom left corner, a padlock icon.