It used to point to this great article. Even though some parts of it are heavily outdated, I think it still is the best documentation on Dart async internals and it would be great if it was published again.

That out-of-date article took a long time to write and review (only one person on the team was able to review everything in it, and he's gone!); I haven't been able to find the time/nerve to update it.

In the short term I could perhaps redirect to the web.archive.org link that @simolus3 pointed to, or add that link to the Medium article. But we really should document the event and microtask queues (dart-lang/site-www#2142).

I've applied the short-term fix of adding a link from the end of the Medium article to the archived article.