[2023] Error 1603

1603/1605 errors are typically a previous other installation stuck, or a problem in the Windows update/install processes.

If you see msiexec OR Paradox Launcher running in Task manager-processes, kill it and try this launcher install again please.


If still no good, do you see Paradox Launcher v2 in the Windows Control Panel to uninstall? If so does it uninstall cleanly, or get an error doing that? You can use this MS tool to clear the stuck install/uninstall:

Fix problems that block programs from being installed or removed - Microsoft Support

The Program Install and Uninstall troubleshooter helps you automatically repair issues when you're blocked from installing or removing programs. support.microsoft.com
THEN Please try this:

uninstall Paradox Launcher v2 from the Windows "Apps and features" utility, if still present.


Delete the following folders if still present:

C:/users/{userName}/AppData/Local/Programs/Paradox Interactive/
C:/users/{userName}/AppData/Local/Paradox Interactive/
C:/users/{userName}/AppData/Roaming/Paradox Interactive/launcher-v2/
To see the AppData folder you'll need to enable View Hidden Items in File Explorer.


exit the Steam app entirely
run steam.exe as the Windows Admin user
run the game from the PLAY button in Steam


IF that doesn't help, in this folder are some .log files:
C:/users/{userName}/AppData/Local/Paradox Interactive/launcher-v2/
Please attach them here.


Note that you can run ck3.exe directly from File Explorer, which bypasses the launcher.