ah, sqlite3 stuff... remove .session file and try again. it means the session is running in the background
This error occurs when more than one process is using the same session file, that is when you run two or more clients at the same time using the same session name.
It could also occur when a background script is still running and you forgot about it. In this case, you either restart your system or find and kill the process that is locking the database. On Unix based systems, you can do the following:
cd into your session file directory.
fuser my_account.session to find the process id.
kill 1234 to gracefully stop the process.
If the last command doesn’t help, use kill -9 1234 instead.