downloading entire game again

[Jwake.7013]

I assume this is on my end, just not sure how yet, still looking into it. So any idea's or anything I'm all ears.I started up my computer this morning (saturday) and I start up my browser to look at stuff and also start up gw2. It gets to the launcher and proceeds to show it's downloading with the little bar at the bottom. I thought maybe an update for a moment since I hadn't played in two days, but then I saw the size and it's the whole game. I check the files and sure enough everything is still there but the new .dat file that is now freshly downloading is the only difference. Just a little baffled by this one. I didn't have any issues with the game last I played and nothing happened with my computer with no real changes since then, so not sure how I lost my old .dat file. Just more annoying then anything as I don't have great internet so it's half a day of downloading.

[Ashantara.8731]

Where did you install the game (i.e., location on drive)?

There are Windows 10 updates that corrupt files. One was released in April, for instance, and you had to uninstall it again (it was removed from distribution later on and replaced with another update). It is always best to google and inform yourself before you download major Windows updates.

[Linken.6345]

Did you maybe change languages?

[Jwake.7013]

Didn't change languages.Checked update history and last thing was a framework update from the 9th.was installed on an external ssd that I have plugged in through a usb3 port. that I never unplug.I realize I forgot to state I last played on thursday night (24th).