I just upgraded from 5.1 to 5.2 to take care of the timeout bug when you install a module and now my home page says this A critical error has occurred. Object reference not set to an instance of an object. I downloaded the upgrade package and just copied all of those files into my current site. Did I do something wrong?

Yes that should work, it may be worth double checking with this tutorial:
How to Upgrade DotNetNuke (Auto Merge Method) (v4.6.2 to v5+)

Have a look in your events log and see if there are more details about the error.

If you can't find any details, and if you have a backup, I would restore a backup. I would then install the live website on a localhost test, and then try the upgrade on your local host test site first.
How to backup a live hosted DotNetNuke website and restore it to a localhost installation

The only thing in the event viewer that is different than what I see on the page is that the process name is w3wp.exe. I have seen that before. Do you have any other thoughts?

Do you have a backup? I would start by reverting back to your backup and bringing your live site back online.

So I restored our website and I am still getting the error. Does the dotnetnuke upgrade change the db also?

Yes, absolutely!

Restoring a website requires that your restore the web directory and the database. 

Backing up a website requires that you back up both the web directory and the database.


Besides tables and data, the database also contains stored procedures and other elements that might get changed in an upgrade.  Tables can change, and the stored procedures that are required to get data in and out of the tables can change.

So I have restored the files and the database and now I get an error saying that the page is in a redirect loop. Do you have any thoughts on what I can do to fix this?

Have you tried all of the old standbys?

• Clear the cache (under Performance settings)
• Restart the application
• Hit CTRL-F5 on your browser
• Clear your browser's cache

Check here. Or here.  Or google for others.

And ... when you fix it, please let us know what your error was.

So this is strange. This website that I was trying to update is our default dnn install. Basically when we build a new website, we copy the files from this site, copy over the database, and run a stored procedure I created to change the settings in the db to make it run under the new website. Even though I couldn't get this to work, I copied the files over to a new website with a new db, and it worked fine. So I then took the files from the new site, copied them back to the original site, and now it is working. Could it have had something to do with me opening the web.config file and saving it again (I had to change the conn string)? That's the only thing I could think of.

Possibly?  But difficult to diagnose from a distance and after you've fixed it ... 

I would have to agree. Thanks for all of your help though.