When I try to run the patch installer it says that it doesn't support my version of the game and asks me to download a new installer. Before I go through the hassle of re-downloading 29 installer files, has anyone actually been able to successfully install the patch without redownloading the game or is it something that needs to be fixed by GoG on their end?

There have been several patches since the release version. This patch is only the last one. It cannot be applied to the release version directly. You would need all of the patches and then apply them in the correct order.

There have only been two hotfixes, one on August 4th and then one today on 8th
https://steamdb.info/app/1086940/patchnotes/
All the other changes were just to the register or soundtrack, nothing with the game files.

That's correct for the Steam version, but on GOG there was a smaller update (~16mb) that preceeded the actual patch 1 download, which appears to have updated some files of the Larian launcher and bumped the version number upto v4.1.1.3624901.

I have the game installed through Galaxy, and this is what its version history currently looks like:

v4.1.1.3630146 - Patch Patch0_Hotfix2
v4.1.1.3624901 - Patch v1 <--- they finally released an offline installer for this
v4.1.1.3624901 - Patch <--- but they forgot to include this part
v4.1.1.3622274

Don't ask me why they split it into two updates on GOG, but I'm not sure it was intentional, because it resulted in some of us ending up with a "Data Mismatch" error on the Larian launcher.

It looks like they FUBAR'd again with the Patch 1 offline installer, seemingly forgetting that they should be including the entire update, so that it patches the game directly from "v4.1.1.3622274" to "v4.1.1.3624901 - Patch v1". Either GOG or Larian are drunk, or someone needs to urgently send them a resupply of caffeine...

That makes a lot of sense, thanks for the breakdown! Thankfully it seems that GoG actually went and fixed their offline patch installers, so now it's possible to get the game to version v4.1.1.3630146 using offline installers, a day late and a dollar short, but we got there, fingers crossed the next hotfix (apparently they need to fix localization credits, among other things), will have a smoother roll out.

I know one way you could make the patching process ten times easier.

Hey Everyone,
Baldur's gate 3 was working perfectly fine until today September 5, 2023. Now the game will no longer launch and my PC is now downloading something titled Baldur's Gate 3 Offline backup installer. When Larian releases a patch are they installed automatically or should I do so manually? Any help would be appreciated.

I have been very persistent about this game. I contacted Larian three times in the last year verifying if my PC could run the game with no issues. Each time Larian stated your PC will have no problems. Unfortunately, since the launch there has been nothing but issues.

Please help
Thank you

I can't reconcile this part: with this part:

Well, thats the advantage of not using a client.

I will just keep playing the "old" Patch 1 until I hear that the current version is fine.