bleepingcomputer[.]com/news/microsoft/microsoft-disables-msix-protocol-handler-abused-in-malware-attacks/
Microsoft disabled it earlier this year to protect against attacks, later re-enabled it, and now has turned it off again. And today Microsoft recommends updating Windows App Installer to v. 1.21.3421.0 or later. To check the version that's installed, type (Get-AppxPackage Microsoft.DesktopAppInstaller).Version in PowerShell & press Enter. I get v. 1.21.3482.0 in this copy of Win11 23H2. To check for available updates and perform any updates, the easiest method is to type winget upgrade Microsoft.AppInstaller at the Command Prompt and press Enter. I show no updates to v. 1.21.3482.0 available. In Win11 you can right click the Start Button and open Terminal. The 1st line will either show PowerShell or Microsoft Windows... Click the down arrow to the right of the + and select Command Prompt or PowerShell to get a new tab for whichever you need. In Win10 right clicking the Start Button will either show you a menu with PowerShell or the Command Prompt depending on your Windows settings. Otherwise the Command Prompt is found in the Start Menu under Windows System, while Windows Powershell is listed on its own. And of course you can always use Search.