I recall an HN comment a year ago that went into some detail about how Twitter botched their webworker implementation, leading to these errors.

But at this point it's safe to say that it's another intentional way of getting to drive users to create an account. It has been too horrendously broken for too long for it to be explained by incompetence.

It seems to happen to me when I have an ad blocker. On occasion I try without an adblocker and don't seem to have the issue. It could just be a coincidence though.

Refreshing never worked for me, although I admit I probably never tried refreshing ten times.

What does work for me is manually prepending www. to twitter.com in the url.