How to regenerate /etc/userdomains file
Backup if exist
mv /etc/userdomains /etc/userdomains_bk
/usr/local/cpanel/bin/userdata_update
and then run
/scripts/updateuserdomains
Notes
Backup if exist
mv /etc/userdomains /etc/userdomains_bk
/usr/local/cpanel/bin/userdata_update
and then run
/scripts/updateuserdomains