Same Issue, It is because of modsecurity.
Match of "rx (/products/index\\.php\\?gallery=|connector=\\.\\./\\.\\./connectors|/admin/(?:structure/views/|[a-z]+/(?:edit|add))|/phpthumb\\.php\\?((?:w|h)=[0-9]+&)?((?:w|h)=[0-9]+&)?src=\\.\\./.*(?:pics|uploads|images)|/site-(?:builder|content)/|/node/(?:[0-9]+/( ..." against "REQUEST_URI" required