ikiterder

Encoding is correct. I went in the server logs and saw a set of such records. Maybe they will help in solving the problem:

[Thu Nov 17 14:45:15.697412 2016] [:error] [pid 5764:tid 1588] [client ::1:50953] \xd0\x91\xd0\xb0\xd0\xb7\xd0\xb0 \xd0\xb4\xd0\xb0\xd0\xbd\xd0\xbd\xd1\x8b\xd1\x85 WordPress \xd0\xb2\xd0\xbe\xd0\xb7\xd0\xb2\xd1\x80\xd0\xb0\xd1\x82\xd0\xb8\xd0\xbb\xd0\xb0 \xd0\xbe\xd1\x88\xd0\xb8\xd0\xb1\xd0\xba\xd1\x83 Illegal mix of collations (latin1_swedish_ci,IMPLICIT) and (utf8mb4_unicode_ci,COERCIBLE) for operation '<>' \xd0\xb2 \xd0\xbe\xd1\x82\xd0\xb2\xd0\xb5\xd1\x82 \xd0\xbd\xd0\xb0 \xd0\xb7\xd0\xb0\xd0\xbf\xd1\x80\xd0\xbe\xd1\x81 SELECT DISTINCT rating_username, rating_userid FROM wp_ratings WHERE rating_username != '\xd0\x93\xd0\xbe\xd1\x81\xd1\x82\xd1\x8c' ORDER BY rating_userid ASC, rating_username ASC, \xd0\xb2\xd1\x8b\xd0\xbf\xd0\xbe\xd0\xbb\xd0\xbd\xd0\xb5\xd0\xbd\xd0\xbd\xd1\x8b\xd0\xb9 include('D:\\Program Files\\xampp\\htdocs\\wordpress\\wp-content\\plugins\\wp-postratings\\postratings-manager.php'), referer: https://localhost/wordpress/wp-admin/plugins.php?plugin_status=all&paged=1&s
[Thu Nov 17 14:45:30.725439 2016] [:error] [pid 5764:tid 1588] [client ::1:50953] \xd0\x91\xd0\xb0\xd0\xb7\xd0\xb0 \xd0\xb4\xd0\xb0\xd0\xbd\xd0\xbd\xd1\x8b\xd1\x85 WordPress \xd0\xb2\xd0\xbe\xd0\xb7\xd0\xb2\xd1\x80\xd0\xb0\xd1\x82\xd0\xb8\xd0\xbb\xd0\xb0 \xd0\xbe\xd1\x88\xd0\xb8\xd0\xb1\xd0\xba\xd1\x83 Illegal mix of collations (latin1_swedish_ci,IMPLICIT) and (utf8mb4_unicode_ci,COERCIBLE) for operation '<>' \xd0\xb2 \xd0\xbe\xd1\x82\xd0\xb2\xd0\xb5\xd1\x82 \xd0\xbd\xd0\xb0 \xd0\xb7\xd0\xb0\xd0\xbf\xd1\x80\xd0\xbe\xd1\x81 SELECT DISTINCT rating_username, rating_userid FROM wp_ratings WHERE rating_username != '\xd0\x93\xd0\xbe\xd1\x81\xd1\x82\xd1\x8c' ORDER BY rating_userid ASC, rating_username ASC, \xd0\xb2\xd1\x8b\xd0\xbf\xd0\xbe\xd0\xbb\xd0\xbd\xd0\xb5\xd0\xbd\xd0\xbd\xd1\x8b\xd0\xb9 include('D:\\Program Files\\xampp\\htdocs\\wordpress\\wp-content\\plugins\\wp-postratings\\postratings-manager.php'), referer: https://localhost/wordpress/wp-admin/admin.php?page=wp-postratings%2Fpostratings-options.php
[Thu Nov 17 14:47:09.854610 2016] [:error] [pid 5764:tid 1580] [client ::1:50985] \xd0\x91\xd0\xb0\xd0\xb7\xd0\xb0 \xd0\xb4\xd0\xb0\xd0\xbd\xd0\xbd\xd1\x8b\xd1\x85 WordPress \xd0\xb2\xd0\xbe\xd0\xb7\xd0\xb2\xd1\x80\xd0\xb0\xd1\x82\xd0\xb8\xd0\xbb\xd0\xb0 \xd0\xbe\xd1\x88\xd0\xb8\xd0\xb1\xd0\xba\xd1\x83 Illegal mix of collations (latin1_swedish_ci,IMPLICIT) and (utf8mb4_unicode_ci,COERCIBLE) for operation '<>' \xd0\xb2 \xd0\xbe\xd1\x82\xd0\xb2\xd0\xb5\xd1\x82 \xd0\xbd\xd0\xb0 \xd0\xb7\xd0\xb0\xd0\xbf\xd1\x80\xd0\xbe\xd1\x81 SELECT DISTINCT rating_username, rating_userid FROM wp_ratings WHERE rating_username != '\xd0\x93\xd0\xbe\xd1\x81\xd1\x82\xd1\x8c' ORDER BY rating_userid ASC, rating_username ASC, \xd0\xb2\xd1\x8b\xd0\xbf\xd0\xbe\xd0\xbb\xd0\xbd\xd0\xb5\xd0\xbd\xd0\xbd\xd1\x8b\xd0\xb9 include('D:\\Program Files\\xampp\\htdocs\\wordpress\\wp-content\\plugins\\wp-postratings\\postratings-manager.php')
[Thu Nov 17 14:47:39.224661 2016] [:error] [pid 5764:tid 1624] [client ::1:51003] \xd0\x91\xd0\xb0\xd0\xb7\xd0\xb0 \xd0\xb4\xd0\xb0\xd0\xbd\xd0\xbd\xd1\x8b\xd1\x85 WordPress \xd0\xb2\xd0\xbe\xd0\xb7\xd0\xb2\xd1\x80\xd0\xb0\xd1\x82\xd0\xb8\xd0\xbb\xd0\xb0 \xd0\xbe\xd1\x88\xd0\xb8\xd0\xb1\xd0\xba\xd1\x83 Illegal mix of collations (latin1_swedish_ci,IMPLICIT) and (utf8mb4_unicode_ci,COERCIBLE) for operation '<>' \xd0\xb2 \xd0\xbe\xd1\x82\xd0\xb2\xd0\xb5\xd1\x82 \xd0\xbd\xd0\xb0 \xd0\xb7\xd0\xb0\xd0\xbf\xd1\x80\xd0\xbe\xd1\x81 SELECT DISTINCT rating_username, rating_userid FROM wp_ratings WHERE rating_username != '\xd0\x93\xd0\xbe\xd1\x81\xd1\x82\xd1\x8c' ORDER BY rating_userid ASC, rating_username ASC, \xd0\xb2\xd1\x8b\xd0\xbf\xd0\xbe\xd0\xbb\xd0\xbd\xd0\xb5\xd0\xbd\xd0\xbd\xd1\x8b\xd0\xb9 include('D:\\Program Files\\xampp\\htdocs\\wordpress\\wp-content\\plugins\\wp-postratings\\postratings-manager.php'), referer: https://localhost/wordpress/wp-admin/index.php
[Thu Nov 17 14:49:34.758725 2016] [:error] [pid 5764:tid 1600] [client ::1:51095] \xd0\x91\xd0\xb0\xd0\xb7\xd0\xb0 \xd0\xb4\xd0\xb0\xd0\xbd\xd0\xbd\xd1\x8b\xd1\x85 WordPress \xd0\xb2\xd0\xbe\xd0\xb7\xd0\xb2\xd1\x80\xd0\xb0\xd1\x82\xd0\xb8\xd0\xbb\xd0\xb0 \xd0\xbe\xd1\x88\xd0\xb8\xd0\xb1\xd0\xba\xd1\x83 Illegal mix of collations (latin1_swedish_ci,IMPLICIT) and (utf8mb4_unicode_ci,COERCIBLE) for operation '<>' \xd0\xb2 \xd0\xbe\xd1\x82\xd0\xb2\xd0\xb5\xd1\x82 \xd0\xbd\xd0\xb0 \xd0\xb7\xd0\xb0\xd0\xbf\xd1\x80\xd0\xbe\xd1\x81 SELECT DISTINCT rating_username, rating_userid FROM wp_ratings WHERE rating_username != '\xd0\x93\xd0\xbe\xd1\x81\xd1\x82\xd1\x8c' ORDER BY rating_userid ASC, rating_username ASC, \xd0\xb2\xd1\x8b\xd0\xbf\xd0\xbe\xd0\xbb\xd0\xbd\xd0\xb5\xd0\xbd\xd0\xbd\xd1\x8b\xd0\xb9 include('D:\\Program Files\\xampp\\htdocs\\wordpress\\wp-content\\plugins\\wp-postratings\\postratings-manager.php'), referer: https://localhost/wordpress/wp-admin/plugins.php?plugin_status=all&paged=1&s
[Thu Nov 17 14:50:44.214686 2016] [:error] [pid 5764:tid 1576] [client ::1:51134] \xd0\x91\xd0\xb0\xd0\xb7\xd0\xb0 \xd0\xb4\xd0\xb0\xd0\xbd\xd0\xbd\xd1\x8b\xd1\x85 WordPress \xd0\xb2\xd0\xbe\xd0\xb7\xd0\xb2\xd1\x80\xd0\xb0\xd1\x82\xd0\xb8\xd0\xbb\xd0\xb0 \xd0\xbe\xd1\x88\xd0\xb8\xd0\xb1\xd0\xba\xd1\x83 Illegal mix of collations (latin1_swedish_ci,IMPLICIT) and (utf8mb4_unicode_ci,COERCIBLE) for operation '<>' \xd0\xb2 \xd0\xbe\xd1\x82\xd0\xb2\xd0\xb5\xd1\x82 \xd0\xbd\xd0\xb0 \xd0\xb7\xd0\xb0\xd0\xbf\xd1\x80\xd0\xbe\xd1\x81 SELECT DISTINCT rating_username, rating_userid FROM wp_ratings WHERE rating_username != '\xd0\x93\xd0\xbe\xd1\x81\xd1\x82\xd1\x8c' ORDER BY rating_userid ASC, rating_username ASC, \xd0\xb2\xd1\x8b\xd0\xbf\xd0\xbe\xd0\xbb\xd0\xbd\xd0\xb5\xd0\xbd\xd0\xbd\xd1\x8b\xd0\xb9 include('D:\\Program Files\\xampp\\htdocs\\wordpress\\wp-content\\plugins\\wp-postratings\\postratings-manager.php'), referer: https://localhost/wordpress/wp-admin/admin.php?page=wp-postratings%2Fpostratings-manager.php