sorry, I am new here.
I have many websites on the same hosting.
I noticed that some websites with the problem are using new version of WordPress.
Other websites with old WP version work fine.
So I tried update some website to WP3.9.1, after that the problem began with my plugins and themes. (No data receieved)
what i have just tried few minutes ago is uploading my backup version of WP-ADMIN and WP-INCLUDES folder
the problem seems to be fixed now.
————-
However, I haven’t tried this solution with my large websites (I only tried with small web). So I am still not sure if it can fix other websites. Because I am afraid that I could mess up my website.
Thank you for all kind suggestions.
