I changed WordPress default theme to support two sidebars. Everything works fine, I can add and remove widgets from any of the the two sidebars and the website works perfect, but:
- When I add a link to my blogroll, although it adds the link to the blogroll, a blank screen appears after pressing "Add Link" button.
- Same happens when I add a new category.
- HTML editor doesn't appear.
I remove famous register_sidebars code from functions.php and just register one sidebar. The problems disappear.