MediaWiki on the Wikimedia projects failed twice. Performance problems caused the Apache servers to fail. There were several issues recognised and many of these have already been fixed.
The problem has everything to do that the fact that the projects are so big that it is hard to predict in advance how it will work out. The fact that a new release is not regularly implemented does not help either.
The situation is now similar to a Chinese juggling act; when will there be a good moment to try the 1.17 installation for a third time, who will be needed and what procedure will be used. The plan seems to be that a decision will be made tonight and tomorrow there it will be show time again.