Cannot access the editing page

If there is a back-end issue with your site we won't be able to help with that. Only SS can deal with those issues. If it is custom code on your site that is causing the issue again it will be difficult for us to help as we can't login to your site to examine the issue in context. Being in the editor vs viewing the site from the outside.

You might try safe mode to see if that helps.

Please post the URL for a page on your site where we can see your issue.

A link to the backend of the your site won’t work for us, i.e. a url that contains /config/.

Please set up a site-wide password, if your site is not public and you've not already done so.

Post the password here.

Adding a site-wide password does not allow anyone to alter your site. It only allows those with the password to see your site.

Please read the site-wide password and how to share a link documentation to understand how they work.

We can then take a look at your issue.

You may find How to post a forum question post useful.