[GNC] longtime user suddenly unable to open gnucash

[Jacob Wegelin]

I have been using gnucash for about 20 years on macos for personal
bookkeeping.
Suddenly today, it refuses to open with the following message:

 	GnuCash could not obtain the lock for /Users/qg/u/Household/GnuCash/wip/JAW.gnucash (which is my file which it also opens).

 	The database may be in use by another user, in which case you should not open the database.  What would you like to do?

When I clicked "open anyway," the application looked like it was loading
and then it went away---the application was not open.

I tried deleting gnucash.LCK and it just made another one.

I reinstalled gnucash, updated my macos and rebooted the computer.

I changed the permissions on JAW.gnucash so it is readable and
writeable by everybody. Exactly the same message.

I tried reinstalling it again after the macos reboot, 
as follows:

https://wiki.gnucash.org/wiki/Installation

https://sourceforge.net/projects/gnucash/files/gnucash%20%28stable%29/
click: download latest version Gnucash-Arm-5.12-1.dmg (184.3 MB)

I made gnucash.LCK read,write,execute by everybody, but the same result.

How do I get GnuCash working again? I use it every day.

Thank you

Jacob Wegelin