In the event of a 500 error on a web page, don't look for the logs in the usual place, error 500 is a fatal error and only the web server produces a message in a special “error.log” file …

It depends on the configuration of your website, two examples below with apache and nginx which are the most common servers.

• apache

ErrorLog ${APACHE_LOG_DIR}/error.log

or in the definition of a virtual host

.../...
     ErrorLog /srv/webs/shop.cap-rel.fr/logs/error.log
     CustomLog /srv/webs/shop.cap-rel.fr/logs/access.log combined
.../...

• nginx

http {
       	  ...
	  error_log /var/log/nginx/error_log crit;
	  ...
}

or in the definition of a virtual host

http {
       .../...
       error_log /var/log/nginx/error_log;
       server {
	        	listen 80;
		        server_name shop.cap-rel.fr;
       		error_log /var/log/nginx/shop.error_log;
                        .../...
	   }
}

It should be possible to find this information on your user account

• example for ovh
• on the console o2switch
• and so on for all hosting providers

Once you've found it, download this error.log file, and if it's “big” open it, delete all the lines whose date is “before the problem” and send us this smaller file … if you're looking for a temporary file-sharing platform that respects the confidentiality of exchanges, ask your service provider to provide you with a link to their infrastructure :)