It seems there is an issue with current beta of eZ Platform and Symfony 2.8.
First load after clearing the caches (with rm -rf) does not load the configuration properly. Presumably, semantic configuration for current siteaccess is not correctly recognized.
Every subsequent load works fine.
This does NOT happen on Symfony 2.7.
EDIT: This also does not happen on 2014.11 when hacked to run Symfony 2.8.
1) Install dev-master of ezplatform. This will automatically install Symfony 2.8.
2) Clear caches with rm -rf ezpublish/cache/*. DO NOT run cache:clear.
2) Add a bogus content_view rule to ezpublish/config/ezplatform.yml. The purpose of the rule is to specify non existing template, which means that we should get an exception.
3) Open the frontpage and notice that the page is loading fine and the exception is NOT thrown, which means that our rule is not correctly loaded first time. Only subsequent loads throw the exception.