I cannot attach image to a slide show

I cannot attach image to a gk image gallery using wp 4.8

I have this strange path in my browser when try to attach image to a gallery
/wp-admin/upload.php?mode=list&attachment-filter=&m=0&s=&_wpnonce=0ec6a37edb&_wp_http_referer=%2Fwp-admin%2Fupload.php%3Fpaged%3D6&action=-1&paged=1&action2=-1&media%5B%5D=1216&_ajax_nonce=35b1c25c69&ps=gallery&found_post_id=121&find-posts-submit=Изабери
And it leads me to a page "It seems we can’t find what you’re looking for.
Perhaps searching, or one of the links below, can help."
Can you please help on this

Could you please provide me your website back-end and FTP access via PM (click the “Private Message” text underneath my avatar) so that I may analyze it?

I sent you PM

Please update your theme to latest version (1.10.2) and disable cache, optimization plugins, then please check again.

1.Hot to update theme
2.How to avoide overwriting changes that i made to css and function.php for example
3.On my loalhost i use duplicator and i can attach image to a gallery page

1. https://www.gavick.com/documentation/wo ... me-upgrade
2. If you didn't use child theme and add your modifications to parent theme files, now you have to compare your files manually
3. Please compare server configuration, PHP version etc.

Is there any module that is not turned of or om by the server side that cause this error or petmission issue because when runing localy on wamp everything is working fine

I found one more issue when try to attach image to a gallery page
Not Found

The requested URL /wp-admin/upload.php was not found on this server.

Additionally, a 404 Not Found error was encountered while trying to use an ErrorDocument to handle the request.

Is there any specific module that needs to be turned on so gallery page module script or api need to work, because i resave permalinks and only have problem with that gallery page

It's a default WordPress feature, did you try to use another theme and attach image to sample page?