Good for you Steve - I’m glad your able to ride!
I’ve managed to successfully update my laptop using a tethered mobile connection and then manually copied over the missing files to my desktop PC (into the Download folder that the zwift updater had created). These are the main files that consistently fail to download, taken from the log file.
This is a workaround to complete the update but is far from ideal. I’m amazed that the updater appears to download each file individually in an uncompressed format.
It is consistent in that the majority of the files are downloaded successfully and always fails on the same files which is what led me to believe this could be an issue with the file repository. So far I’ve worked out that for me cdn . zwift . com is resolving to 4 load balanced cloud front servers. The IP addresses for these change periodically (which could explain perhaps how some people didn’t do anything apart from reboot or try and update at a different time).
I did attempt to manually download the missing files as the location details are all contained within the log file. However I’m unable to manually download files from the file server apart from the version XML file as the other files appear to require authentication to download (403 error).
I’m wondering if cloud front is closing the connection at some point during the download for some reason but I guess no one really cares. Unfortunate for anyone who isn’t technical and is faced with this issue as they will likely just not ride and/or stop their subscription.
For anyone else with the problem you will probably have to download (by running the installer) the missing files reported in the log file through another internet connection (perhaps on another PC) and then copy them across to your desktop if required like I did.