Edge updates (and also others that include something called the Edge WebView2) fail with 0x800951dd on some computers, but not others. Hm. 9 is FACILITY_SECURITY. The event log is full of “Windows Event Reporting”; dozens of events for each installation attempt. What is going on?

From the log (cleverly stored in %PROGRAMDATA%) is appears that the updater really wants to phone home, and if it cannot, it prefers to crash. Where the security thing comes from is unclear, particularly because 0x51dd is undocumented. Direct HTTP is blocked, so the installer prematurely departs this mortal coil. And tries again. And again. And again.

On computers where it works the log shows that the updater figures out where the proxy is, so the quick fix (until I figure out how to make the updater behave) is to tell the updater the same on the problematic systems.