Same issue here, I attempted to re-cache my topic tags and it failed instantly, showing that error message. Seems to have wiped the tags from the topics list on the forums, but the tags are still there when you view a topic.
UPDATE LOW_PRIORITY IGNORE `core_search_index` core_search_index SET `index_tags`='Army List' WHERE index_class like '%forums%' AND index_class like '%forums%' AND index_item_id=28518 LIMIT 1
IPS\Db\Exception: Unknown column 'index_tags' in 'field list' (1054)
#0 /home/gagqlnoi/public_html/ips4/system/Db/Db.php(836): IPS\_Db->preparedQuery('UPDATE LOW_PRIO...', Array)
#1 /home/gagqlnoi/public_html/ips4/applications/advancedtagsprefixes/modules/admin/manage/tools.php(343): IPS\_Db->update('core_search_ind...', Array, Array, Array, 1, 3)
#2 [internal function]: IPS\advancedtagsprefixes\modules\admin\manage\_tools->rebuild()
#3 /home/gagqlnoi/public_html/ips4/system/Dispatcher/Controller.php(85): call_user_func(Array)
#4 /home/gagqlnoi/public_html/ips4/applications/advancedtagsprefixes/modules/admin/manage/tools.php(26): IPS\Dispatcher\_Controller->execute()
#5 /home/gagqlnoi/public_html/ips4/system/Dispatcher/Dispatcher.php(129): IPS\advancedtagsprefixes\modules\admin\manage\_tools->execute()
#6 /home/gagqlnoi/public_html/ips4/admin/index.php(13): IPS\_Dispatcher->run()
#7 {main}
Tool to fix database errors didn't solve it for me either.