Problems finding the root folder for blocks
In a project that had been upgraded from EPi6 R2 (originally an EPi4 site) with PageTypeBuilder to EPi7 the Global Library in the block section was missing.
When checking the parameters globalBlockFolderId and siteBlockFolderId in sitesettings of episerver.config I noticed they was set to 3 that is all correct in a new site. Since this was an upgraded site and the concept of blocks being all new this obviously was wrong.
To find out the correct id I constructed a simple SQL
SELECT pkID FROM [dbo].[tblContent] where fkContentTypeID =
(SELECT pkID FROM [dbo].[tblContentType] where [Name] = 'SysContentFolder') AND ContentPath = '.1.'
This will return the pkID you must set in the globalBlockFolderId and siteBlockFolderId parameters