Проблема "Driver Error" IP.Board 3.4.9 при переходе с MySQL 5.6 на 5.7:

Driver Error
There appears to be an error with the database.
If you are seeing this page, it means there was a problem communicating with our database. Sometimes this error is temporary and will go away when you refresh the page. Sometimes the error will need to be fixed by an administrator before the site will become accessible again.

если переключить драйвер с mysql на mysqli, то видим это:

Warning: require_once(/home/mysite/public_html/forum/ips_kernel/classDbMysqli.php): failed to open stream: No such file or directory in /home/mysite/public_html/forum/admin/sources/base/ipsRegistry.php on line 2693

Fatal error: require_once(): Failed opening required '/home/mysite/public_html/forum/ips_kernel/classDbMysqli.php' (include_path='.:/opt/cpanel/ea-php56/root/usr/share/pear:/home/mysite/public_html/forum/ips_kernel/') in /home/mysite/public_html/forum/admin/sources/base/ipsRegistry.php on line 2693

Как лечить? Спасибо.

Привет а случайно у тебя щас версия php 7.1 не стоит?

Перепробовано, как с 5.6, так и 7.2, а также попытка переключения на mysqli драйвер. Или 500 ошибка сервера или ошибка выше.

В логах эта ошибка:

Date: Thu, 21 Feb 2019 02:44:19 +0000
 Error: 1055 - Expression #3 of SELECT list is not in GROUP BY clause and contains nonaggregated column 'mysite_forum.t.tag_meta_app' which is not functionally dependent on columns in GROUP BY clause; this is incompatible with sql_mode=only_full_group_by
 IP Address: 144.76.38.40 - /forum/index.php
 ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
 mySQL query error: SELECT t.tag_text, COUNT(t.tag_text) as times, t.tag_meta_app, t.tag_meta_area
                    FROM core_tags t WHERE  tag_meta_app IN ('core','members','forums','downloads','gallery','calendar','blog','membermap','pmviewer','searchactivity','mudd','promenu','shoutbox')
                    AND t.tag_aai_lookup IN( SELECT p.tag_perm_aai_lookup FROM core_tags_perms p WHERE
                 ( ( FIND_IN_SET(2,p.tag_perm_text) ) OR ( p.tag_perm_text='*' ) ) AND p.tag_perm_visible=1 ) GROUP BY t.tag_text
 ORDER BY times DESC
LIMIT 0, 50