Weird. I have got this on 5 of my sites, but 5 others updated OK.
The 5 that failed are with A2 hosting, LiteSpeed server, which may or may not be related (never had an issue before, in several years.)
There are plenty guides to fix > There has been a critical error on this website
Same here, update went fine on several sites but other sites the critival error.
Same here. Only had problems with 2 WooCommerce sites, other sites no issue. With support from my hosting provider they are fixed again, but it’s still not clear what caused this error. Guess you need to ask your hosting provider for support or for the errorlog.
But many problems with update to WP 5.9, please check other topics in forum.
Guido
I use ManageWP, and updated 10 sites on the same hosting account at the same time. Never been an issue before, but I’m *guessing* it overloaded my server resources – perhaps some sites updated OK, and others then timed out (leaving the sites down with incomplete WP updates.)
In facts, checking cPanel, looks like it may have been the IO which hit 4MB/s (screenshot).
