If the launcher starts to load but crashes within a couple of seconds, or it was working until a graphics driver update, it may be crashing due to a check on the graphics driver. Editing or replacing a configuration file to skip the check should get it working again. See the section below the general troubleshooting suggestions for details.
Are you shutting down all non-essential programs (especially anti-virus) before starting the game? Firewalls can cause conflicts (generally on startup or loading screens) and overlays from graphics tweaking/monitoring programs or chat programs can also caused issues.
Try verifying local files: in the Steam library, right click on the game and select Properties, switch to the Local Files tab and then click on the 'Verify Integrity of Game Files...' button.
With the GOG version, in the (optional) Galaxy client, select the game, then the settings icon at the top right (beside the Play button) and under Manage Installation select 'Verify / Repair'.
Try starting the launcher directly from the '..\SteamApps\common\Baldurs Gate 3\Launcher\LariLauncher.exe' executable.
For the game, try optionally exiting out of the Steam client, and starting the game directly from the '..\SteamApps\common\Baldurs Gate 3\bin' folder, by right clicking the executable (bg3.exe for Vulkan, or bg3_dx11.exe) and running as administrator.
If necessary, try right clicking the executable, select Properties, switch to the Compatibility tab and check off the 'Override high DPI scaling behavior' option (set it to Application), run as administrator and disable fullscreen optimization, and maybe set a Win 7 or 8 compatibility mode. In Windows 7, check off the option to 'Disable display scaling on high DPI settings', disable desktop composition and run as administrator.
Especially if you get a .Net error message trying to start the launcher from the executable, try reinstalling the .Net Core redistributable, either from the '..\Baldurs Gate 3\DotNetCore' install folder (3.1.8), or this download (3.1.16, at the time this was last edited). Alternately, in Windows Control Panel, Programs and Features, try right clicking the Microsoft Windows Desktop Runtime entry (3.1.x), select Uninstall and then Repair.
If the launcher worked previously, try copying and pasting %LocalAppData%\Larian Studios into the location bar in Windows Explorer, hitting Enter, and then in that folder rename the 'Launcher' folder and try starting the launcher again. If that helps, the first time the launcher starts it may take a little longer, as the cache is rebuilt. This is unlikely to be an issue with a new install.
If you check the Event Viewer, does that give an error code or 'Faulting Module' file name that might help identify the cause of the crash?
- click Start (or WinKey-R), then type "event viewer" into the search box. in Windows 10, 'event' should bring up 'View event logs'.
- after starting the Event Viewer, expand 'Windows Logs' in the left column and select 'Application'
- in the center column, look for a recent error for the game (maybe sort by Date and Time, or search for 'LariLauncher', and 'bg3' if applicable)
- check the information under the 'General' tab below the list of events, starting with "Faulting application name..."
If that does not help, please copy and paste %LocalAppData%\Larian Studios\Launcher\Logs into the location bar in Windows Explorer, hit Enter, and from that folder contact support with the runlog.txt file.
Also include a dxdiag report (WinKey-R, type in dxdiag and hit enter, then when it finishes loading click on the 'Save All Information...' button and save the report somewhere handy), check the '..\Baldurs Gate 3\Launcher' folder (and '...\bin\db\attachments' or “...bin\db\reports”), for the gold.log file, and if there are any CrashDump files being created, zip a few together to include.
If you take a look at the runlog.txt file and recent attempts to start the launcher end after starting a graphics driver check, editing a configuration file can get the launcher to skip that check.
Copy and paste %LocalAppData%\Larian Studios\Launcher\Settings into the location bar in Windows Explorer, hit Enter, and in that folder open the preferences.json file in Notepad, or other text editor, add the line below at the bottom (before the closing bracket), put a comma at the end of the former last line, save, close the file and try the launcher again.
It will look something like this (it may start with a line specifying the launcher language, and there may be additional lines):
and after editing:
Alternately, download this zip file and extract the contents into the Settings folder, overwriting the original (or rename it first, if you wish).
If there is a problem with the launcher saving the configuration file, it may not exist. In that case, in the %LocalAppData%\Larian Studios\Launcher folder, manually create the Settings folder if required, and then extract the downloaded file there.
If that does not help, please contact support with the updated runlog.txt file, etc (as above).