Trying to upgrade an existing installation(test) with data pages
in it (a 2.0.2b installation) allows me to get to the data pages
but not the CMS.
I upgraded by copying cms, jsparty, and sapphire from a clean 2.1.0rc1
installation. Then doing a db/build?flush=1 and a home?flush=1
I get the error when attempting /admin (which is redirected to /Security/login
and I never actually get the login page) and generates the error:

Fatal error: Call to undefined method stdClass::allMethodNames() in /var/www/html/w/sapphire/core/Object.php on line 203

However taking a clean 2.0.2rc2 installation, and upgrading it I
can access the cms as normal.

My installation was originally based off of 2.0.2b. I have tried installing
a clean 2.0.2rc2 then overlaying the mysite, and assets from
my 2.0.2b directory and restoring the database.
That works (running as a 2.0.2rc2) to access data and cms.
But then when I attempt to upgrade to 2.1.0rc1 from there, I have the same
problem with accessing the CMS.

It obviously is something to do with the database but I don't know what.
I can point my updated installation code (2.0.2rc1) to the clean
2.0.2rc1 database and it works to access the CMS (of course the formating
is from my css and templates and I don't have access to my data since
I'm pointing to a clean database).

Since I have the problem in the login of the cms (since I can't get past
that. I looked at the differences (my upgraded database and a clean 2.0.2rc1
database) in the Group and Member tables. They match with the expected changes
in dates, names, and passwords.

Looking at sapphire/core/Object.php the error is coming from "addMethodsFrom",
could this mean that there is a problem with a function in one of
my code (page) extensions? Would that have not been caught in the db/build?flush=1
or the access of the page (after flushing) but caught in the CMS initialization?

Looking at some of the other comments, I built my installation from modifying the tutorial (so
I didn't have Blackcandy). In the clean installations I installed with the blackcandy template.
Could this be a possible cause?

I've actually been having the problem with the daily builds from 7Sep and 9Sep as well.