William Severance Thanks for your detailed suggestions. Sadly before I tried them, I'd already attempted to restore the site to how it was before the upgrade, & made a bit of a hash of it. What I'd done was to simply restore all the files from backup, but the backup wasn't from immediately before the upgrade, but from some time before, so on some pages I got errors about Skins or something - I believe this was because the Skins installed at the time the file backup came from were different to those that the database 'thought' were installed. So as the site wasn't yet live, & as it only contained about nine or ten pages with any content on, I thought I'd just revert to the default Skin, then go into each page in Edit mode & save a copy of the HTML from each section, then I could completely set the site up again from scratch, & paste back in all the HTML. I was halfway through doing this when I started trying your suggestions, & no doubt because of this, I can't now get the site to work at all! So I've now extracted the contents of the HtmlText table, which appears to contain all the HTML code, & will now start again with the site, then paste in the HTML. So thanks for your assistance, but next time I will be very careful when upgrading sites!

William Severance - following the nightmare I had last time trying to update my DNN software, I remembered this time to UnBlock the .zip file (what a stupid idea of Microsoft's that was!), & the whole process went swimmingly! So thanks for the suggestion, & now my confidence is being able to update what will soon be my live business website is restored.