Just implemented a fix that got it working on a users PC.
Make the user is is signed out of MYOB in their web browser.
1. Open `regedit` as admin
2. Navigate to `HKEY_LOCAL_MACHINE\SOFTWARE\Classes`
3. Right-click `Classes` → New → Key → name it `myob-arl`
4. Click the `myob-arl` key, double click the `(Default)` → set value to `URL: MYOB AccountRight Protocol`
5. Right click `myob-arl` → New → String Value → name it `URL Protocol`, leave value empty
6. Right click `myob-arl` → New → Key → `shell`
7. Right click `shell` → New → Key → `open`
8. Right click `open` → New → Key → `command`
9. Right click `command`, double click `(Default)` → set value to:
```
"C:\Program Files (x86)\MYOB\MYOB AccountRight 2026.2\Huxley.Application.exe" "%1"
```
(note: update the executable path to suit your needs)
Launch AccuntRight again and sign in, this time after signing into MYOB in the browser a pop up should appear asking to launch AccountRight click OK, if that happens you know it's working.