In DotNetNuke, "dbo. GetPortalAlias ByPortalID doesnt exist" is an error that can occur when an install was not done correctly. it happens most often when creating a new install of DotNetNuke.
The usual cause of this error is not setting up and configuring all prerequisites before starting to install DotNetNuke. what happens is that the install fails dues to something that is not setup, or has the wrong permissions. This causes the install to stop part way through, with some tables and stored procedures created, and others not created.
To fix this error if it occurred during a new install, simply delete the database and create a new blank database. Then fix the prerequisites that were not set correctly and start the install again. You must delete the database because a the half installed database is useless, and it is quicker to start again than it is to repair it.
If this error occurred during an update, do not delete your database .. it has all your previous information in it! Instead, you should first restore your database backup .. you did make a backup before starting to upgrade, right? ... then fix the prerequisites that were not set correctly and start the upgrade again.
To see what the install prerequisites for DotNetNuke are, read our post easy DotNetNuke installation guide