If you encounter some of the errors below and especially when trying to access a page or the front page of a site collection or site then the problem might be related to missing page layout or master page references.
This may be due to the fact that you have migrated content from an older SharePoint version and the content database is referencing an older hive version.
So check that you solution packages are installed using compatibility mode:
install-spsolution -identity solution.wsp -webapplication “site url” -gacdeployment -CompatibilityLevel All
Relying on fallback logic in VghostPageManager::getGhostDocument() for document: ‘C:\Program Files\Common Files\Microsoft Shared\Web Server Extensions\14\Template\SiteTemplates\somesite\default.aspx’
This collection already contains an address with scheme http. There can be at most one address per scheme in this collection.