admin-ajax.php 500 error

Hi,
few days ago I try to upload image on my blog so I can insert in post, but when I click “Add media” images grid wont load. I figure out it’s admin-ajax.php.
I get “500 (Internal Server Error)” for that file, and when I open in browser, I see only zero (“0”).
I tried: disable all plugins, back to default theme, optimize table, delete EVERY cache (I have no cdn), manualy delete cache leftovers, re-install from admin panel, manualy re-upload new WP (save only content and config), test from another browser, PC, VPN, from mobile… In debug mode admin-ajax.php have status 200 but no content in “response” tab.
Error_log it’s ok, nothing there. Server admin answer me and say there is not errors in any log file (server, apache, my account.. nothing).

I notice problem after updating WP to 4.3

And yes, I have SSL, maybe thats is problem? But I have SSL for two years, no problems before.