Recently I took several DNN installs from DNN 3.2 to DNN 4.  I ran into two issues after completing the installs that are worth a mention:

• Users were unable to use the core Documents module to download files
• Uploading files or installing modules broke

Fortunately, both of these issues are easy to solve.

The first error is caused by a change in how permissions are handled for accessing files in the portals/0/ directory (or whichever directory represents the current portal).  Previous to DNN 4.4 access to these directories was available to any user, any role.  In DNN 4.4 the File Manager page now gives control to the portal administrator to allow 'View Folder' (Read) and 'Write to Folder' (Upload) permissions to any role for any directory.  Checking the box next to All Users for 'View Folder' allowed my files to now be downloaded as before.  One interesting symptom of this change is that the you can add a document to the Documents module as Admin, but users of the site won't see anything listed at all.  They won't get an Access Denied error when they try to download, the download item won't appear at all!

The second issue presents itself with an error such as the one below:

Failure:

ExceptionSystem.IO.FileNotFoundException: Could not load file or assembly 'SharpZipLib, Version=0.81.0.1407, Culture=neutral, PublicKeyToken=null' or one of its dependencies. The system cannot find the file specified. File name: 'SharpZipLib, Version=0.81.0.1407, Culture=neutral, PublicKeyToken=null' at DotNetNuke.Modules.Admin.ResourceInstaller.PaInstaller.ReadZipStream() at DotNetNuke.Modules.Admin.ResourceInstaller.PaInstaller.Install() WRN: Assembly binding logging is turned OFF. To enable assembly bind failure logging, set the registry value [HKLM\Software\Microsoft\Fusion!EnableLog] (DWORD) to 1. Note: There is some performance penalty associated with assembly bind failure logging. To turn this feature off, remove the registry value [HKLM\Software\Microsoft\Fusion!EnableLog].

The issue is that DotNetNuke 4.4 now incorporates compression into the core.  Great!  Unfortunately, if you were already running Blowery compression on your site, there are now two .dll's in your /bin directory with the same code (which is what the error above is trying very hard to tell you, but not doing a very good job).  The solution is simple, just delete the Blowery* and ICSharpLib* in the directory (blowery.Web.HttpCompress.dll, blowery.Web.HttpCompress.xml, ICSharpCode.SharpZipLib.dll & ICSharpCode.SharpZipLib.dll in my setup).