This often happens if Steam is not open or if the fix files were moved to the wrong folder. Verify that the files are in the same folder as the game's executable.
Use a stable version of Proton (e.g., Proton Hotfix or Proton Experimental). Troubleshooting Common Issues phasmophobia-fix-online-v9-3-rar
Launch the game using the main executable (usually Phasmophobia.exe ). This often happens if Steam is not open