Saving page redirects me to post listing page with an xxxx/xxx/edit.php url.

I have searched up and down looking for solutions.

I have tried:
??Changing the .htaccess file
??Adding a time zone to the php.ini file
??Raising file size with php.ini
??Disabling plugins
??Deleting inactive plugins
??Checking error log – so far nothing

NOTHING has worked for me. I can’t save/update ANYTHING, whether it’s a form, a post, a page, a theme .php file. Literally nothing.

Any suggestions on how to fix this?