I believe this error has been around for some time, well before I upgraded to 4.3, but I see this in the system logs constantly:
The URL of page the error occurred on was https://www.site.com/gallery/image/1544-l-312e8a50fed7cb1c3c55f828cab5fc66/
IPS\Db\Exception::1064
SELECT COUNT(*) FROM `gallery_images` WHERE image_album_id=48 AND image_id<>1544 AND image_= IS NULL
You have an error in your SQL syntax; check the manual that corresponds to your MariaDB server version for the right syntax to use near 'IS NULL' at line 1
#0 /home/user/public_html/system/Db/Select.php(378): IPS\_Db->preparedQuery('/*IPS\\gallery\\_...', Array, true)
#1 /home/user/public_html/system/Db/Select.php(440): IPS\Db\_Select->runQuery()
#2 /home/user/public_html/system/Db/Select.php(361): IPS\Db\_Select->rewind()
#3 /home/user/public_html/applications/gallery/sources/Image/Image.php(898): IPS\Db\_Select->first()
#4 /home/user/public_html/applications/gallery/sources/Image/Image.php(1032): IPS\gallery\_Image->fetchNextOrPreviousImages(1, 'ASC')
#5 /home/user/public_html/uploads/template_15_dd7fa6b771626a3f041bfec4dc0472c8_view.php(971): IPS\gallery\_Image->prevItem()
#6 /home/user/public_html/system/Theme/SandboxedTemplate.php(58): IPS\Theme\Cache\class_gallery_front_view->imageFrame(Object(IPS\gallery\Image))
#7 /home/user/public_html/uploads/template_15_dd7fa6b771626a3f041bfec4dc0472c8_view.php(340): IPS\Theme\_SandboxedTemplate->__call('imageFrame', Array)
#8 /home/user/public_html/system/Theme/SandboxedTemplate.php(58): IPS\Theme\Cache\class_gallery_front_view->image(Object(IPS\gallery\Image), '\n<div data-cont...')
#9 /home/user/public_html/applications/gallery/modules/front/gallery/view.php(326): IPS\Theme\_SandboxedTemplate->__call('image', Array)
#10 /home/user/public_html/system/Dispatcher/Controller.php(96): IPS\gallery\modules\front\gallery\_view->manage()
#11 /home/user/public_html/system/Content/Controller.php(50): IPS\Dispatcher\_Controller->execute()
#12 /home/user/public_html/applications/gallery/modules/front/gallery/view.php(61): IPS\Content\_Controller->execute()
#13 /home/user/public_html/system/Dispatcher/Dispatcher.php(146): IPS\gallery\modules\front\gallery\_view->execute()
#14 /home/user/public_html/index.php(13): IPS\_Dispatcher->run()
#15 {main}
The "AND image_= IS NULL" is breaking the query. I'm not entirely sure what's corrupted here. I was able to upgrade to 4.3.5 without issue.
I've cleared the cache and am using the default template unmodified.