Can’t Delete Items

I have an old and outdated blog I’m trying to print for sentimental reasons. I updated WordPress and related plug-ins, including Anthologize. But it’s being buggy. I can’t delete any item (part or post/page), this gives me an “error has occurred” message, and nothing is deleted. Also, sometimes the post and page titles don’t show up, so I can’t see what I’m working with, but if I refresh enough, they come back. But now, I got an “error has occurred” message and all the posts I had added are blank, in the preview and export.

I can keep starting over, export each category separately, and try not to make any mistakes, but this will still take quite a while. Is there a way I can get the errors to stop? Is there something else I can update? Is this an out-of-date plug-in altogether and I should try something else?

Thank you for your time.

Carol