If you are getting this issue wih CPanel:
failed to open session lockfile: FILE=/var/cpanel/sessions/raw/:Up5nKwLkFgQF_Ke_yEsgb_w9gMl2FzDSPpHdrus6DAOcD30Xt1tEgWy41BwsSQC5.lock, No such file or directory at /usr/local/cpanel/Cpanel/Session.pm line 261.
df -i : to check the usage of inode space.
if it showing 100% used then
rm -rf exim : to delete the exim file
Issue will resolved