i have this issue too after having to reinstall the launcher due to an "Exit Status 1603" that prevents the launcher from being launched. worse, the "Exit Status 1603" error appeared again today so i have to reinstall the launcher...which still says OP's "unable to update" error message.
support ticket suggested VPN-ing to the US but that didn't work.
We don't know if you have the same cause as the OP as they never provided logs. In future please make a new thread. Thanks.
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:
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.