We've been running with version 4.0.2.1 for a while and its time to upgrade (years overdue).

We have built up quite a set of customizations to our base package, which includes updates to some of the core files and markup. 

I've run through and compared all of our changes to the 4.0.2.1 version, and then basically re-made the customizations to the 4.9 version of the code, to the point that i'm ready to upgrade an existing site.

I've read several of the wikis, and following their directions I started to upgrade. I backud up the files/database and then overlaid the 4.9 files over the existing site.  I then applied our updates on top of that. I then browsed to the website and as expected it started through the 'installing umbraco' screens.

But it hung on step 3 with '20% connection opened'.  Digging into the code (p.aspx.cs), it seems that there is a glitch where if it can connect, the database is not empty, but "(installer.CurrentVersion == DatabaseVersion.None || installer.CanUpgrade)" is false, it just exits out of installOrUpgrade() without setting progress or errors into the helper.

I tracked down 'CanUpgrade()' and in SqlServerInstall.cs it seems to require "CurrentVersion == DatabaseVersion.Version4_1", which is just slightly newer than what we have.

So my question: is there a way to upgrade just the database (such as SQL scripts to run) to get from 4.0.2.1 to a version that can be upgraded to 4.9? I would prefer not to have to upgrade the entire code base between multiple versions and go through the install screens for each.

Thanks in advance for all help and advice

-e