My client wishes me to roll everything back to 4.8.4 and either wait for an upgrade path that works or find a product that does.  

At a minimum I need to find a migration and test methodology that lets me test DNN upgrades off-line on a second TEST instance.  I have a clean/virgin DNN 5.5.1 install and a backup copy (actually many...) of my database.  What I need is some help either modifying the database to run with the new DNN instance or to modify my DNN instance to work with my 'restored' database, on GoDaddy.  This seems like it should be straightforward...

I was able to backup and restore code and data to and from production tweaking only sql connection strings and/or machine key settings in web.config.

The portal alias hint was also helpful.  Slick.  I am sooo grateful.  I will always be able to put up a backup site in a heartbeat.

Bad news is I can break even a virgin DNN w/ Forum install with my live user db in a matter of minutes...

Will try to narrow it down; it involves some combination of:

-initial Post(s) by host or admin
-Avatars off
-Moderation off (0 threshold)
-"Discussion" name changed on 'first' forum (to "Web Site")

I may have changed one or two other settings.

Once the error begins, nothing makes it stop.  I will try restoring the working db (I saved it in-process) and repeating my steps under the delusion someone may be able to use the info.

Bob