Blastoidea
Same here – and I have found the reason!
You are using display lock, right?
There is a new update for Session on GitHub and in the own repository of Session on F-Droid with version 1.17.3.
If you have installed it and then browsing all submenus of preferences menu, don't activate display lock!
All other settings are working as usual, but in the moment, when you activate display lock in submenu Privacy, first entry, your Session app will crash!
If you can't reach the settings because the app is always crashing after the start, tap long on the app icon, select “App Info” and then delete “cache” and “memory content”.
Attention! All of your chats and contacts will be deleted! Be sure, you know your recovery phrase!
Only the last 14 days will be recovered by using the recovery phrase – but today there is no other way to get the app running again – maybe tomorrow or a little bit later there will be a newer update 1.17.4 (?) which fixes all easy with installing it?
If you have very, very important and/or older chats and contacts, then it's maybe worth to be patient and wait for the next bugfix from Session's Dev team…
I have sent my crash reports to CTO Lee Jeffereys and they will fix it.
Tip: Use your password vault to store Session IDs from your important contacts.