[2022] EU4 "Launching the game failed" on steam & DLCs aren't working from EU4.exe

What antivirus app do you use? You need to make sure all these apps are in its exceptions lists:

eu4.exe and dowser.exe (in the Steam EU4 folder)
C:/users//AppData/Local/Programs/Paradox Interactive/launcher-v2.2022.1/paradox launcher.exe
C:/users//AppData/Local/Programs/Paradox Interactive/bootstrapper-v2.exe

IF that doesn't help, also set each of those .exe files (EXCEPT eu4.exe !) to run as the Windows Admin user.

Then the game should run from Steam/our launcher, and enable all the DLCs.

Good luck!