I had an odd MySQL problem when I installed the 10.1.5 update. One of my databases was giving me this error when I tried to select it:
mysql> use dbnameIt turns out that the permissions for the database were somehow changed. To correct it, enter the following in the Terminal:
Can't read dir of './dbname/' (Errcode: 13)
%cd /usr/local/mysql/data/Replace dbname with the name of the database, and you'll need to be an Admin user to execute the command 'sudo' command. That should clear everything up.
% sudo chmod u=rwx,g=rx,o= dbname