Joplin portable don't start anymore. I always get a fatal error message.
I downloaded the latest portable app again, but it is still the same behavior.
It looks like some data in the database is corrupted. To fix it you will need to do this:
Open the file database.sqlite in JoplinProfile using a database viewer such as https://sqlitebrowser.org/
Go to "Browse data"
Open the "settings" table
Find the entry with key "syncInfoCache"
Copy the data under in "value" cell and paste it in a text editor
Delete the "value" and save
Now Joplin should start, however please note that the sync state has been lost so I'm not sure what will happen. I think nothing special with filesystem sync but to be sure make a full backup of your data.
By the way would you mind sharing the content of the "syncInfoCache" you copied earlier so that we can see why it was corrupted in the first place?
It looks like your external drive is corrupted so the database is not being saved properly. I would suggest before doing anything else to make a copy of your profile on a different drive.
Do you have a backup of your data somewhere? Because you should probably restore all data from it.
First also run a disk check on your drive to confirm that there's indeed a problem there.