The new Wordpress can't work anymore with the Atahualpa theme! Can anyone tell me what to do?

In what way is it not compatible? I have it running and it looks to be working fine.

If you are having an issue, are you sure it is not a plugin conflict?

can't open media library when I search for featured image and when I change theme, it's fixed. Also deactived all plugins, nothing happens. Atahualpa is my favourite theme and can't work without

EDIT: I also have a copy from my Wordpress and it hasn't been updated or changed for a while and it got the same problem. So I think it's somethig with new PHP version?

what version on PHP? You can finde the version by adding a text file called phpinfo.php containing the following:

<?php 
if (! ($xmlparser = xml_parser_create()) )
{ 
   die ("Cannot create parser");
}

phpinfo();
 ?>

and then running it with 'your domain.com/phpinfo.php - once you run it and get the php version delete the file so hackers can't find it and run it. FYI: I have access to php v7.0.27 and featured images work fine.

What verson of Atahualpa?

do you see anything in your error.log file?
do you see any messages if you edit the wp-config.php and set:

define('WP_DEBUG', true);

fixed it!

I had to copy header and footer from atahualpa-child to atahualpa, choose atahualpa and it was fixed

Oh...so you were using a child theme of atahualpa?? That would have been helpful to know.

Well glad you figured it out and I’ll close this.