Upgraded the server to the latest version. It's gone more purple.
Also, apparently the asset-compile step can fail silently, which then makes the server start but refuse to return any pages.
You can see the errors if you know how to look at the log:
> journalctl -f -u mastodon-web
And if your console has enough lines in it because that's a very long error with the important bit at the top: Can't find an asset in the manifest.
But running the precompile says there's nothing to do:
> RAILS_ENV=production bundle exec rails assets:precompile
> Everything's up-to-date. Nothing to do
Even if you do a clean first:
> RAILS_ENV=production bundle exec rake assets:clean
Ponderous. 
Seems you can force it to actually do the work by removing the manifest:
> rm public/packs/manifest.json
And then it's all like:
> Compilation failed.
Oh. Good. Not going to tell us why then?
Apparently you can ask for more output by editing a line in config/webpacker.yml to
> webpack_compile_output: true
Then you get the overload instead.
I think it was maybe running out of memory?
Free up memory by stopping everything:
> sudo systemctl stop mastodon-sidekiq
> sudo systemctl stop mastodon-streaming
> sudo systemctl stop mastodon-web
And compile assets once more:
> RAILS_ENV=production bundle exec rails assets:precompile
Ahha. If you can read this then that worked.
Restart the services:
> sudo systemctl start mastodon-sidekiq
> sudo systemctl start mastodon-streaming
> sudo systemctl start mastodon-web
And actually reboot to check that it all comes back without more fiddling.
In other news, I have upgraded my #nextcloud
Apparently I was a few versions behind. Oh. Maybe quite a few.
Click the updater, and it just does it all and then says okay.
But beware: That's only upgraded one version. You're not done in your quest yet.
So do that an embarrassing number of times but with no issues even though I have a weird install with custom apps.
It's afraid the indexes it wants would take too long to run by itself so wants me to:
> sudo -u www-data php occ db:add-missing-indices
But in fact it takes no time at all.
Yeah yeah, I should upgrade php. I think that will break other things though. Not today.
I think I might have to press that button again next week. I thought there was a new one just around now but this is double 0 7.
I'm well practiced now at least.
In other news, I have upgraded from Buster to Bullseye, after edting /etc/apt/sources.list with the name change:
> apt update
> apt dist-upgrade
A few instances of deciding to keep local edits, thanks for asking.
Better reboot that as well. Make sure it all comes up okay...
OH NO DEBIAN, you have run apache without the php plug in. I mean stop. Stop. That is very bad.
Seems to be some kinda 7.3 vs 7.4 thing. Might as well get it over with.
> sudo apt remove php7.3
> sudo apt install php7.4
Cautiously restart apache and it's not exposed but it's erroring and nextcloud hides the logs in a weird place.
Apparently I also need:
> apt install php7.4-xml
Humm. Something weird with the database. I suspected this was coming:
> apt remove mysql-client mysql-server
> apt install mariadb-client mariadb-server
That seems to be fine.
Good....
Oh. Nope. One more, and I mean also now you mention it:
> apt install php7.4-curl
> apt install php7.4-gd
> apt install php7.4-zip
> apt install php7.4-mbstring
> apt install php7.4-intl
Also you gotta give php more than it deserves, editing /etc/php/7.4/apache2/php.ini to
> memory_limit 1024M
Otherwise seems okay.
One final reboot for snapshot..
And there she floats with a new php engine and bullseye. Continuously running since 1999, give or take the odd day.
I do not expect the jump to 8 to be as seemless.
Was hoping that'd all be done by noon.