Yahoo hosting – WordPress Updates gone wonky

Site’s been up a couple of years, hosted on Yahoo, built from a template originally and tweaked over time with random plugins. All has been well until recently – wordpress fails to update automatically. Currently there are 7 plugins needing updates. When I try to update any one of them the site goes blank. I have to restore via yahoo database utilities, to my last saved backup. Then it’s rinse and repeat again from there. Not only can I not update these plugins, but I cannot delete them either. My only option for deletion is via yahoo file manager or ftp. Dorking around on my own I managed to turn my dashboard all white, no control of anything, but the site still worked on the front end. I renamed my plugins folder via yahoo file manager and now I have a dashboard again. But I still cannot update to the latest version of wordpress.

The closest thing to a hint I can find is this message which has appeared only twice upon update failure:

Downloading update from https://downloads.www.ads-software.com/release/wordpress-4.8.1-partial-0.zip…

Unpacking the update…

Verifying the unpacked files…

The update cannot be installed because we will be unable to copy some files. This is usually due to inconsistent file permissions.: wp-includes/version.php

Installation Failed

Anyone have a clue as to how I can get this site updating properly again?

Thanks in advance