How to deal with "A network timeout error occurred. Please try again later." in iTunes Connect

I first encountered this error about a week ago, while trying to set up a new purchase item for an existent app. Given the recommendation to try again later, I assumed it's a transient error and I ignored it.

About a week later I tried again, with the same result:

Hmm, now this doesn't look any more like a transient error, unless a really unlikely coincidence it at play here. In any case I alerted Apple. Then I figured I should also try with a different browser, and sure enough it works fine with Safari.

So if you're getting this too, try switching to Safari and you may be able to work around it.