This time, everything went very smoothly! Only minor tweaks needed after, and nothing broke. Debian might be years behind, but at least their update process rarely breaks :)
Took a bit longer than expected. The server migration to take advantage of new hardware didn't go well and I had to contact Linode's support to fix it on their end. All back now, and with lots more disk space and fully-functional backups.
Once the Wednesday maintenance fixes the backups, I'll be spending time Friday updating the operating system the server runs on. Hopefully things won't actually be down for 3 hours, but chances are there will be a few little things that need cleaning up as part of the update.
Starting 5PM Pacific Wednesday / 00:00 UTC Thursday, I'll be taking the Tower database offline to fix backups then restart to take advantage of a hardware upgrade.
Looks like it's a Chrome/Webkit thing. It reads and honors the EXIF orientation field for inline images, but not when they're displayed. Seems to be a really, really old bug (like from 2010, but I guess still not fully fixed).
In order to apply an important security update, I need to reboot the VPS (server) that the Tower runs on. I'll be taking the opportunity to do some other maintenance as well, and expect it to take about an hour in total.
Start time: 9PM PDT Saturday, Oct 22nd (4AM UTC on Sunday, Oct 23rd)
Jalen: The vBulletin 4 hash algorithm is md5(md5(password) + salt). Some amount of effort required, especially for strong passwords, but definitely pretty weak by modern standards.
Got the update to fix this (the vulnerable part of the forums was disabled in the meantime), so there's going to be a quick emergency maintenance to apply it and re-enable things. Should be just a quick blip.
Done!