Fixed: Opera / Opera GX crashing on startup (restaring 4 times then closing)

Hey everyone, if your Opera GX is crashing immediately on launch, restarting 4 times in the background, and then just dying, I finally found the fix after hours of troubleshooting.

Here is what didn't work for me

• Reinstalling the browser or deleting AppData profiles.
• Downgrading to older versions.
• Trying normal Opera (same crash).
• Disabling the Nvidia GPU, updating drivers, or disabling Nahimic audio services.
• Trying to launch it with commands like --disable-gpu or --disable-vulkan.

Why is it happening?
If you have ever used sandbox tools (like Codex Sandbox), they sometimes mess up your Windows folder permissions. Specifically, they delete a permission group called All App Packages from your Local AppData folder.

Chrome and Edge don't care because they install in Program Files, but Opera installs directly in your user profile folder (AppData). When Opera tries to start its sandboxed GPU process, Windows blocks it from reading its own files (like opera_browser.dll), causing a crash loop.

The Fix:
You just need to tell Windows to let sandboxed apps read your AppData folder again.

1. Click the Windows Start menu, search for cmd, right-click Command Prompt, and select Run as Administrator.
2. Copy and paste these four commands one by one, hitting Enter after each:

icacls "%LOCALAPPDATA%" /grant "*S-1-15-2-1:(OI)(CI)(RX)"
icacls "%LOCALAPPDATA%\Programs" /grant "*S-1-15-2-1:(OI)(CI)(RX)" /T
icacls "%LOCALAPPDATA%\Opera Software" /grant "*S-1-15-2-1:(OI)(CI)(RX)" /T
icacls "%APPDATA%\Opera Software" /grant "*S-1-15-2-1:(OI)(CI)(RX)" /T

(Note: The /T part might take a minute or two to finish—just let it run).

Once they are done, launch Opera GX normally. It should open right up!