Kobo (the site) did something about a year (+) ago that disabled that check.
You CAN go to
https://pgaskin.net/KoboStuff/kobofirmware.html and grab a copy the manual way.
(There is a
how to at the top)
And keep an eye on the MR Kobo forum. Someone announces when a new one appears (

Wait a few days, just in case they oops'd )