[2023] Stellaris Won't Launch From Steam - "Installation package could not be opened."

imgonnahurtu said: Per the thread title, Stellaris will not launch from steam. Any attempt to do so results in the attached error window appearing.

I have tried reinstalling both Stellaris and Steam, verified file integrity, and also launched the game (successfully) from the Stellaris application in the actual steam folder itself.

As far as I can tell the issue seems to be tied to the Launcher-Installer-Windows. To the best of my knowledge the first launch of Stellaris is supposed to launch this and then install the launcher (obviously). However, while I can run Stellaris the application itself just fine, even manual attempts to start the launcher-installer result in the same error message I get when trying to launch directly from steam.

Thanks for any help.

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.  

tmurph13 said: I have the same launch issue on Steam PC except I don't even get an error message. It just aborts.

In which case it is very likely not the same problem. Please try the above anyway, and make your own thread with those logs if it does not help. Thanks.  

Please do that process again, but isntead of running the game try this updated installer:
https://launcher.paradoxinteractive.com/v2/paradox-launcher-installer-windows

IF that doesn't help still The 1603/1605 errors we see there are typically a previous other installation stuck, or a problem in the Windows update/install processes.

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

Otherwise run the Update app in Windows, does it load okay, find anything to apply - whether a patch, update, or whole new Windows 10 version? If so do that and reboot, then 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

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