EW7 says schedules created in EW6 are locked by another user
Try rolling back to EW 7 build 184.108.40.206 at the bottom of the Downloads page under additional downloads.
We had this same issue. Turned out it was trying to open a spurious file (some jpg in a temp directly in the user's Windows profile which no longer existed so it could never be resoled). This only manifested after the schedule was copied from one system to another (same version of EW listed below)-- one person was creating the master schedule and then pushing it to the machine where it would be displayed during Services. On the second machine: The file open of the schedule would fail on the bad file embedded in the schedule ("file not found") and then if you tried to open the schedule again, you got the "locked by another user".
We ended up overwriting the user's database with a copy we had on hand. That seemed to work. The user affected was on Windows 7 ( May 2021) and had version 220.127.116.11.
The user does has some odd behaviors starting with 18.104.22.168 -- all the graphics in his EW schedules show black on his display. But the graphics which he places as the backgrounds for schedule items are there on the 2nd machine when the schedule is opened there.
I have just upgraded from EW6 to EW7 and when I try to open schedules created in EW6 it says that the files are locked by another user and I cannot open them.