Broken Windows Update

Summary
After updating to desktop-v0.5.22 on Windows, the Buzz window loads a blank dark screen showing a browser-style "File not found — It may have been moved, edited, or deleted. (ERR_FILE_NOT_FOUND)" error instead of the app UI. This is fully reproducible and is not caused by a corrupted update, cached state, antivirus, or environment issue — see troubleshooting below.

Environment

OS: Windows 10.0.26200.0, x64
Buzz Desktop: v0.5.22 (broken) / v0.5.20 (last known working)
WebView2 Runtime: 152.0.4191.62 (current)
Installer source: buzz.xyz (Buzz_0.5.22_x64-setup_alpha-unsigned.exe)

Steps to reproduce

Have Buzz v0.5.20 (or earlier) installed and working normally.
Trigger an update to v0.5.22 (either via in-app "Update" button, or by fully uninstalling and installing v0.5.22 fresh from buzz.xyz).
Launch Buzz.
Window shows a blank screen with "File not found / ERR_FILE_NOT_FOUND" instead of the app.

Reproduced this twice independently: once via the in-app updater from a working install, and again via a completely clean uninstall.exe + fresh v0.5.22 installer download (ruling out a corrupted download/update).

What I ruled out

Corrupted/partial download — re-downloaded fresh from buzz.xyz, verified file version via VersionInfo (0.5.22.0), still fails.
Stale WebView2 cache/session — cleared %LocalAppData%\xyz.block.buzz.app\EBWebView entirely, still fails on relaunch.
Antivirus/EDR interference — Windows Defender shows no detections, Controlled Folder Access is off.
Stale/broken shortcut — Start Menu shortcut target resolves correctly to the installed exe.
WebView2 Runtime itself — up to date and healthy, used successfully by other apps on the same machine.
Disk space — ~660GB free.