I have been having the same issue lately, where I am logged in on the new site, but any redirect to the old site (and trying to log in there) creates a loop of errors. Clearing all Finnair.com cookies from my browser helped though, login worked on both versions of the site after that.

I've recently had the merry-go-round of clicking "go to old site to book awards" only to be bounced between several stages of log-in pages and then returned to the new site. Rinse-repeat. After a 4-5 attempts it suddenly works and I am at the old site.
It is a mystery how they can keep this set-up month after month.

Needed to use the old site but the booking engine doesn't work, the process stops > access denyed... Using chromebook.

It has always been a mission impossible to get the luggage allowance right on any communication from Finnair. This is the closest to the truth that they have managed to get by far.
https://cimg3.ibsrv.net/gimg/www.fly...904df83962.jpg

Really? I need to contact CS to change my seat reservation? I tried Chrome, Firefox and Edge without avail. This sounds nuts.

And no, it makes no difference if a flight was upgraded or I paid straight for J.

Can anyone log in to old AY+ pages anymore?
I just get stuck on a redirect that never loads, then gives up and return me to non-logged-in status. Looks like I'm logged in to new web though. However, all links in new page links back to old page logged out.

I just tried. For me, it works just like before, ie logging in on the old page automatically takes one to the new page, but then there's a link taking one back to the old page (for award bookings etc). After that, one stays there and it works like before.

Tried 3 different browsers, still no luck.

Strange. Try private mode?

I'm using Firefox 70.0.1.

Metoo. But I have several blockers installed, which sometimes interfere. But Opera and safari (clean installs) has the exact same behaviour.
Log in to new page succeeds. Clicking link "go to old page" links to the new bookings page, but logged out. Clicking "log in" at old page just redirects but the link has a new form. It has a "ticket" ID, and a reference to a private IP-number (like a local behind firewall server)

Are you behind a Firewall? Maybe it catches the cross-site scripting necessary to log you in to the old site using the cookies of the new website.

I am. However, that is not something that has changed lately, so unless they altered the scripting in a bad way, then firewall probably isn't the root cause.

An interesting thing is that no links work on my usual computer. Moving to a brand new computer (located in same network) then some links work. I can from that computer go to MMB (which is in the old site)

So this is clearly a new version of the login procedure that does not work in Mac OS 10.13. I guess they decided everyone need to buy new hardware again.

I had the pleasure of experiencing a new bug:

Upgraded wife to J with my points, and as expected Y points were not credited. Requested retroclaim through website - nothing. Contacted CS, who sent me an email saying points already credited to another airline.

As neither of us have any other FF cards, I called AY to ask if they have been hacked. This was not the case, but apparently doing the upgrade partially added my FF number to her booking, which the system interpreted as belonging to another airline (at least according to the CS explanation).

If the points were actually credited to your FF account (the other airlines), that would have been good bug ;)

Sigh, I try to make a booking using the voucher as partial payment method - > Does not work in App, not in normal website on mobile mode (using phone, one must manually choose desktop-mode in browser settings) and when I try to do all that..this is what happens.

https://cimg0.ibsrv.net/gimg/www.fly...59cc3b60fc.jpg