A bit less than half of my subscribed Yahoo calendars are working fine with VM, the remainder are getting the above error message (interestingly, there was no obvious notification of this error within VM until I manually tried to subscribe, but I then noticed that those calendars hadn't been updated since I ran VM yesterday).Unable to update subscribed calendar "(my calendar name)"
The remote server returned an error: (403) Forbidden.
I am able to normally access all the 'Forbidden' calendars via my browser, they all have the option "Allow apps that use less secure sign in" enabled (in case that's needed) and none of my VM (or Yahoo) settings have changed from when all the subscriptions were working correctly.
Any suggestion as to what else I can try to fix the problem?
UPDATE: I searched through the forum for "Forbidden" to see if this (or something similar) has happened before. It seems to have happened in February of 2015 to kansaifixer (which then seemed to require a VM update to fix). Based on those posts, I checked my Windows update history, and while there were a few updates this week (including some Framework updates), there have been successful Sync attempts for all my calendars after those updates. The only updates done today were definition updates for Microsoft Security Essentials and Windows Defender, and I can't see how that would affect a Sync attempt (especially since it fails with only some of the calendars).