I have a problem when i login website by facebook and redirect or click to page home error 500
but login by google not error

my website okhalal.biz

If the error is in home page it's likely most probably not related to the Facebook login. Enable the error reporting and debug in Joomla to get error details instead of generic 500 server error.

error on web server

[Sun Oct 09 14:01:16.673801 2016] [fcgid:warn] [pid 668814:tid 140172179830528] [client 180.183.112.64:52469] mod_fcgid: stderr: PHP Notice: Undefined variable: gantry in /home/okhalalb/domains/okhalal.biz/public_html/templates/easyshop/error.php on line 15, referer: https://okhalal.biz/my-account.html
[Sun Oct 09 14:01:16.673856 2016] [fcgid:warn] [pid 668814:tid 140172179830528] [client 180.183.112.64:52469] mod_fcgid: stderr: PHP Fatal error: Call to a member function init() on null in /home/okhalalb/domains/okhalal.biz/public_html/templates/easyshop/error.php on line 15, referer: https://okhalal.biz/my-account.html

if not related to the Facebook login ,why google login no problem
only Facebook login problem

Pls help or advice
Best Regards,
Ans

I don't know the problem is part of the template not of the facebook login.
The error is the following included in the template, probably they are attempting to do a wrong operation:

PHP Fatal error: Call to a member function init() on null in /home/okhalalb/domains/okhalal.biz/public_html/templates/easyshop/error.php on line 15

Also i tried your website through a FB login and it works with no errors at my end.
You have to contact template developers to fix definitely however.
John