If you don't like the legacy Edge, simply move on. Let me preface this with not everyone wants to do this. (Unless you enable Edge legacy side by side) The update failure doesn't have to do with restoring Edge legacy, though removing Edge Chromium is a necessary step to use Edge legacy. And if Edge Chromium fails to install, then the Cumulative update will fail to install.

It will re-install it through Cumulative update every month starting from April. Update : Microsoft really want you to use Edge Chromium. There is an issue on some systems where Edge Legacy would crash immediately after launching, and no fix has been discovered so far. When you go into Edge settings, edge version should be '44.19041.1266.0' because edgehtml is updated as part of the system.

Update : The workaround still works on the latest 20H2 security patch (2021-10), given if you can get a copy of the binaries from a March 2021 build. It has to do with RuntimeBroker activation of companion processes and it's more complicated than I can figure out. After installing 2022-01 security patch, Edge would no longer launch. Update : The workaround is officially dead (on my system, if it didn't die sooner as others reported).

Microsoft edge legacy download