Since the update today (04/07/2021), I cannot add new blog posts. When clicking the “Add Post” in either the admin sidebar or the top bar, it throws at 404 error with a URL of /index.
I have tried to resave permalinks, but the problem persists.
I have tested it on my test site and it’s working fine for me using the latest version of the Jevelin theme as displayed in the attached screenshot.
To confirm whether this is a theme issue could you please temporarily use the Twenty Twenty theme on your site. If everything works fine then it’s the theme issue or else it is your website issue.
The problem persists when I switch themes, so I was wrong in thinking it was the theme. I am working through my plugins right now to try to isolate the problem. Thank you for checking on your end.