Debian 10 - Tor browser black screen Connect to Tor

Debian 10. Tor browser windows are suddenly all black, including the Connect to Tor window.

/var/log/messages shows the following warnings:
kernel: [  xxx.xxxxxx] audit: type=xxxx audit(xxx.xxx:xx): apparmor="DENIED" operation="exec" profile="torbrowser_firefox" name="/usr/bin/lsb_release" pid=x comm="firefox.real" requested_mask="x" denied_mask="x" fsuid=x ouid=x

The cause is a bug related to Apparmor, bug report:
https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=942901

Apparmor status can be checked with:
apparmor_status

It is possible to remove Apparmor and restart the machine to workaround the problem:
apt-get remove apparmor apparmor-utils libapparmor-perl; reboot

This is however weakening the security since Apparmor is removed.

There is a better workaround in the bug report that keeps Apparmor.

Create or edit this file:
/etc/apparmor.d/local/torbrowser.Browser.firefox

Fill it with:
owner /{dev,run}/shm/org.mozilla.*.* rw,
owner @{torbrowser_home_dir}/updater ix,

Note the commas on the end of each line.

Then restart Apparmor:
systemctl restart apparmor

Then restart Tor browser.