I just spent the last 24 hours straight tracking down bugs in the upgrade process. There are some big ones and finding their causes is very difficult. I finally got it to work. Here are some suggestions:
1. BACKUP both your database and website files. I know everyone says this, but man, this is important. Also, make sure you have .net 3.5 installed - it says only 2.0 is required, but you will get a bunch of error messages if you don't have 3.5.
2. The first set of issues I ran into after following the provided upgraded instructions had to do with XML parsing objects - and I couldn't get my site to load at all. Here is what I needed to do (after restoring my inoperable system): make sure all of your modules are upgraded to the latest version for DNN 4.x. Some of the modules, even if they are only a year or so old and working fine, access some procedures that are no longer supported on DNN 5. There is no warning about this. Make sure you upgrade all the modules (do not install the versions for 5.x - just 4.x). This will save you a lot of headaches. After you install the upgraded modules, make sure they work and then BACKUP your database and website again.
3. Now, per the instructions, extract the files, overwriting the existing files. DO NOT RUN THE install.aspx/installmode=upgrade yet. First, make a backup of your web.config file and the release.config file and then rename the Release.config to web.Config. There are some new settings in web.config and it is easier to copy your old settings for your site into the new web.config file than try to figure out what needs to be added to your old file. make sure you copy your machine key and database connection settings. AND - unlike the directions state - DO NOT REMOVE THE LINE ABOUT SQL SERVER EXPRESS - this will create an error (found this out the hard way). Just comment out the setting for SQL Server Express and make sure you uncomment the SQL Server connection string and make sure the database connection is correct.
4. After updating the web.config file, now run the install.aspx?installmode=upgrade.
5. If your reasonablly lucky, this will work and you will have a site that almost works. There are still some show stoppers. First, and this is critical and completely undocumented, go to the Admin | Languages menu and make sure there is a language selected AND that it is active (even if your site is English only). If you do not have an active language set you will get all sorts of errors - for example, you will not be able to save any site settings and (see this post: http://www.dotnetnuke.com/Community/Forums/tabid/795/forumid/107/threadid/328639/scope/posts/Default.aspx ) you will not be able to add any blog entries!
6. If you are getting other errors in the blog module (e.g., null object), it is a skin container issue. The blog module expects a setting in the container named PROVIDERNAME. If you only have a couple of containers, it's not that difficult to fix, but if you do, it's a real pain. See this post on how to fix:http://www.dotnetnuke.com/Community/Forums/tabid/795/forumid/92/threadid/324869/scope/posts/Default.aspx
Other changes:
You no longer install/remove modules from the Modules link. It is done from the Extensions menu choice under host. When you click on Extensions all the modules installed will be listed with an edit option next to it. You will not see any option to install extensions UNLESS you are in the Edit mode.
I hope this helps others with the upgrade process.
Regards,
Charlie