I had Moodle 2.0 (from git repo today) installed and running for about half an hour. Created a course added some users, logged out, couldn't log back in. Debug is as follows.... does this mean anything to anybody before I start digging...
Default exception handler: Coding error detected, it must be fixed by a programmer:
Trying to reference an unknown block region side-pre
Debug:
* line 779 of /lib/blocklib.php: coding_exception thrown\n
* line 881 of /lib/blocklib.php: call to block_manager->check_region_is_known()\n
* line 894 of /lib/blocklib.php: call to block_manager->ensure_instances_exist()\n
* line 298 of /lib/blocklib.php: call to block_manager->ensure_content_created()\n
* line 824 of /lib/outputrenderers.php: call to block_manager->get_content_for_region()\n
* line 66 of /theme/standardold/layout/general.php: call to core_renderer->blocks_for_region()\n
* line 612 of /lib/outputrenderers.php: call to include()\n
* line 570 of /lib/outputrenderers.php: call to core_renderer->render_page_layout()\n
* line ? of unknownfile: call to core_renderer->header()\n
* line 964 of /lib/setuplib.php: call to call_user_func_array()\n
* line ? of unknownfile: call to bootstrap_renderer->__call()\n
* line 315 of /login/index.php: call to bootstrap_renderer->header()\n
Howard:
I had the 'standardold' theme selected...
But, Howard, Moodle 2.0 is a brand-new version, with lots of lovely brand-new themes to choose from. Why on earth did you select that obsolete standardold theme? Nostalgia? 
And I confirm that there is a bug. IMHO that obsolete theme should be removed from 2.0 distribution.
Joseph
I actually wanted to do some before and after shots about upgrading from 1.9 to 2.0. I wanted to concentrate on the functionality. The whizzy new themes tend to "get in the way", visually.
Anyway, thanks for confirming that. It's quite important as selecting this theme breaks your site and will require some database tinkering.
As an aside, is it not a nasty oversight that selecting a broken them can lock you out of the site?
Anyway, thanks for confirming that. It's quite important as selecting this theme breaks your site and will require some database tinkering.
As an aside, is it not a nasty oversight that selecting a broken them can lock you out of the site?