Hi everyone!

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).

The manifest of the module is valid (it's Dynamic Registration 4.1).

My installation steps are (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 toHosts) - 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()?

Any hint is greatly appreciated. Thanks!

However, I found the reason: the viewstate of the container skin was partly disabled, probably to minimize the page size. Re-enabling every viewstate along the line did the job.