Getting recovered db files to work on rebuilt server
If the user that the MySQL server does not have permissions to read and write to the files, then the server will not recognize the table. Usually the server runs under the 'mysql' user.

I would first stop your mysql instance before trying to change the ownership.

Once that is done, then (from a non-root user) do sudo chown mysql bsf_session.* in the directory with the files.

You could also try to change the group (sudo chgrp mysql bsf_session.*), however having the files as the same owner as the server is the best option.

If you do not have sudo privileges or root access, then you will need to contact whoever does to have them change the ownership.