The last few days (today is 2020/8/2) pressing the reload button on Synaptic poisons the boot partition. Yes Synaptic is not brilliant software. You can use apt with xterm.
If it is already 2 late for you, you can save your data.
1 Select advanced at boot and recovery.
2 After the luks and login at # (root) type StartX
It did happen to me 7 times in the last 3 days.