I wonder if a newer bbPress build will be required which can be taken from trac (or via svn).
Let me tinker a bit and see if they changed cookie methods (yet again, sigh)
CONFIRMED: WP 2.6 breaks cookie sync
and I get a endless-loop login by WP 2.6
Many people seem to confirm similar cookie problems:
https://wordpress.org/support/topic/188964
https://wordpress.org/support/topic/188870
So what next?
Is this an issue of configuring wp 2.6 and bbpress 0.9.0.2 correctly to fix this problem?
Or is a software-update necessary?
There was a large commit to trunk a few days ago that upgraded most of the cookie stuff.
We might have to sit tight for a 0.9.1 release or something like that.
I figured out a work-around to get into admin area on WP 2.6 but this will “knock out” your bbPress login as you switch back and forth:
https://wordpress.org/support/topic/188964/page/2?replies=41#post-803992
Okay, some bbPress users may be able to get it to work with WordPress 2.6 by adding to your wp-config.php
@define('ADMIN_COOKIE_PATH', '/blog/wp-admin');
where “blog” is your blog’s actual path. If it’s in the webroot, just take out “blog” entirely and leave '/wp-admin'
My installation seems to work with just that slash “/” on it own, but at least it working. I added the below into my wp-config.php file
@define('ADMIN_COOKIE_PATH', '/');
I have tried it with '/blog/wp-admin' and that didn’t seem to work, at all.
yes, that seems to fix it (at least for me):
from this thread: https://wordpress.org/support/topic/188964/page/2#post-803992
go into your wp-config.php
and add this line:
@define(‘ADMIN_COOKIE_PATH’, ‘/’);
NOTE ‘/’ will be your blog path.
If you find that ‘/’ doesn’t work, make it ‘/blog/` or whatever your path is.
The trouble is that the developers on the WP side, in their wisdom 
decided to re-use an existing cookie name for a new purpose and change the cookie path.
The idea is higher security as the admin cookie in theory should only get transmitted when you are entering the admin section.
This is why you need to try deleting all your cookies (for your site) after installing WP 2.6
If that fails, try my define fix above.
Note that changing the cookie path to ‘/’ takes you back to the lower level of security that WP 2.5.1 and earlier had. There’s a particular WP mod who’s upset with me for even suggesting this but I figured the idea is to get you up and running ASAP first until they address this later.
Also, none of this truly fixes WP 2.6 to work properly with cookie integration with bbPress 0.9.0.2 – that’s going to require an upgrade on the bbPress side.
(couldn’t get the quote to work) from _ck_ post above: ” Also, none of this truly fixes WP 2.6 to work properly with cookie integration with bbPress 0.9.0.2 – that’s going to require an upgrade on the bbPress side.
ahh this must be why I am having trouble with single sign-on? In the past hour, I have tried everything in all the other posts about this topic to no avail. Unless I tried every combination/setting with the configs except the right one, of course.
You cannot use WordPress 2.6 with bbPress 0.9
There are major cookie changes in 2.6.
It’s going to be awhile before there is a version of bbPress that will work with 2.6, so stick with 2.5.1
