Question

When I upload any module in System->Extensions in DotNetNuke 5.6.3, running on a Windows 2008 R2 server, IIS 7.5, after the correct module information is displayed and I hit next, I receive the error message

Message: DotNetNuke.Services.Exceptions.PageLoadException: Object reference not set to an instance of an object.. —> System.NullReferenceException: Object reference not set to an instance of an object.at DotNetNuke.UI.WebControls.FieldEditorControl.CreateEditor()at DotNetNuke.UI.WebControls.FieldEditorControl.DataBind()at
DotNetNuke.UI.WebControls.PropertyEditorControl.AddFields(Table tbl)at
DotNetNuke.UI.WebControls.PropertyEditorControl.CreateEditor()
[…]

and the module is not installed. The file system of the web has not been touched, so I thought it was a permission problem, but even allowing user Everyone to do everything doesn’t help (after making sure the ApplicationPoolIdentity user has been allowed full access as well).

Any hint is appreciated.
The manifest of the module is valid (it’s Dynamic Registration 4.1).

Update: Installation steps (note: I am using a German installation of Windows 2008, so some translations might not be accurate)

1. Log in as Hosts Super User (Admin)
2. Either navigate to System->Extensions or System->Module Definitions (System might be identical to Hosts) – I tried both
3. In System->Extensions, click Installation assistant for extensions
4. Select file to upload
5. Click next
6. Description of uploading package appears correctly – click next
7. Error message Object reference not set to an instance of an object. appears on top of the page. Log View shows stack trace as partly displayed above.

What can cause an error in DotNetNuke.UI.WebControls.FieldEditorControl.CreateEditor()?

What kind of permissions could be missing?

Update 2: By step-by-step debugging, I found out that the view state is broken, for some reason. The method BindPackage() in DesktopModules\Admin\Extensions\Install.aspx.vb doesn’t find the current Installer Package. I have not yet found out why the viewstate breaks. It is enabled and huge in the rendered page source.

Answer 1

As described in Update 2, the page’s viewstate is lost in DesktopModules\Admin\Extensions\Install.aspx.vb. Simply replacing ViewState by Session works (but this workaround may be lost after the next DNN update).

Update (in case someone has a similar issue):
The DNN container that was used had its viewstate turned off! This results in all kinds of weird behaviour, but it took time to track that error. Now it’s obvious.