I keep getting Update failed E9, GOG.com servers returned an unknown error. And it won't let me launch the game without the update.

I have the same problem. When I reinstall it, I also get an error.

Same here. I guess that something is wrong in GOG servers. Meanwhile you can play by starting the Larian Launcher from the install directory (it's inside the "Launcher" directory, no big deal)

I'm having this issue also, and vaguely remember it occurring similarly a few patches ago. IIRC, that lasted a couple of days, so the best thing might be for support tickets to let GOG know it's happening again. That's what I've done.

Me too and i tried unistalling both GOG launcher and the game but nothing works

Same here (gets stuck of 90MB of 107MB). The Verify / Repair function does not help.

Same here. Other games seem fine. Now I can't even play this game since I tried reinstalling it. It just gets update failed almost immediately. Hopefully GOG fixes this.

It is not only Baldur's Gate 3.
Other games, like Black Geyser, have problems too.

Same for me. Updates for other games seem to work (Stellaris, Age of Wonders 4, Rogue Trader).
My BG3 is stuck at 79%, 102 MB / 119 MB.

Same problem here.
It reaches 87% and fails with the same error E9.

Same here, posted on the steam update news to bring attention to it.

Same here. i don't even reach 2%...:(

yepp, same here, super weird

Me as well, update keeps failing around there. Repair also doesn't work.
I can start the game, but I can't join my friends that are on the new patch through Steam.

I'm not seeing the error code E9 (or any other, not sure where this appears), but this seems like the same issue.
Haven't tried a re-install since people say it also fails.

Yeah I wouldn't try it, I uninstalled assuming I just didn't have the hard drive space to patch the update as usual, and now the game's just gone. Hopefully they fix it soon