Clear your cookies. That should do it. You might also try clearing your cache first but will probably need to do cookies.
Help, can't switch back to V2!
I just was able to switch on my laptop without issues. So maybe just a temporary glitch. You might also try it when logged out ... that may work by using chess.com/switch.
this will allow going back and forth.
Just to note, that was giving the same error when I tested on my mobile browser earlier.
I know, but it's not an automatic function. For instance, my browser is set to clear cookies every time I quit. Does yours do that on your device? phone or tablet?
No, it's a manual process unless I browse in private mode.
Ayyyy, it worked! Yeah, clicking the "Old Chess.com" and the /switch link both gave the same error message I showed.
But clearing the cache thingy did the trick! Thanks friendos!
And extra thanks TY! The shoe on head thing, though! That's the real gem here!!
How long will we still be able to enjoy v2?
No idea for sure but my guess is that v2 will be gone by the end of the year.
How long will we still be able to enjoy v2?
No idea for sure but my guess is that v2 will be gone by the end of the year.

Yeah, I figured v3 would be default for all new accounts by the end of Summer. Which aligns well with that, though I assumed v2 would stick around a little longer.
Chess.com should poll their users on which version they like better before pulling the plug on V2. It should give them more information on when it is optimal.
Have you tried clicking "Old chess.com"? It usually works for me... but if it doesn't, try clearing your caches and restarting your browser. Should definitely work...
Btw, it's nice to see that you're looking for a daki and plane tickets to Japan!
That's not likely. They have been working on v3 for a few years and they won't support two versions and won't write off off the time and money already spent to keep a version of the site that is hard to update and has problems of its own.
@TY shoes on head a best! I make sure to always have that in my screenshots in the tabs to confuse people!
Ita a shame with V3 because it looks like q mobile site but I much prefer V2 on mobile. Maybe if they fix all the bugs and make things smooth. Hopefully it takes them 20 years to finish that so I can use V2 in peace for that period.
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I've been struck by the worst thinkable V3 bug - not being allowed to switch back to V2 after intending to temporarily try something out in V3. Please fix, this is awful! I get this access violation error message when I try switching back. what's the deal?! Is V2 staff privilege? Not fair!