Not able to edit pages – redirected to Posts page

I’m trying to update my website pages, but once I’ve changed the text in the editor, when I try to preview or upload the changes I am just directed to the Posts page in WordPress (which is a change from originally when I was directed to the “Page not found” on my website)

This has occurred after updating to the most current release of WordPress and updating some plugins. I have deactivated all my plugins to see if it was one of them but it has made no difference. Does anyone have any ideas?

Thanks