ah, yes, that was the message I got; but I think once or twice I've managed to accidentally 'get around' that, one time when some changes were lost (just some movies put into 'ordered' and 'wished', that dissappeared, the file had reverted back to the previous version), and one time when the whole file was somehow overwritten with the empty version.
the problem with the portable version (when I tried to install it and gave up) is the same one as I've seen on two of my full installs (one of which is much older than the one which worked, and on a much older install of windows 7, and one of which is much newer than the one which worked, and a newer windows install

) - three copies of the 'setup' process spawned and nothing more happened (same way that the updater process did when trying to update, and same way the installer did when I downloaded the file from the link you suggested.
I haven't gone near windows 10

(one other possibility for a cause at least of the data problems, rather than the updating problem, is that the network drive and a parity drive have to spin up when changes are made if they aren't already spinning, which can take 10-15 seconds; so some kind of network latency thing...can't see how that would affect the installer/updater programs though)