Category Archives: Development – SP

I am working on a  web part that reads an  XML template (applies to any files)  from a “Document List” on MOSS. Here is the code:

Pitt is the hostname when setting up the “Web Application” in  MOSS, in this case the web part is trying to connect to itself (localhost, pitt).

When the Web Part comes up, it throws an 401  Exception on the xmlDocument.Load().  I thought it was something to do with permission and should be very easy, ended up spending more than 2 days to figure this out.

Configuration:

Windows 2003 Enterprise with SP2,  MOSS 2007, Visual Studio 2008, .NET 3.5 SP1

What I have tried:

1. Using “System.Net.NetworkCredential” to hardcode the username/password for the resolver, still got 401 error

2. Checked the Identity Application Pool, MOSS Service, Farm Administrator, Web Application Policy (Central Admin), Site Collection administrator, all permission related area, etc.

3. Deleted  the MOSS Web Application and re-created it, didn’t help

Symptoms:

1. Internet Explorer on the MOSS server worked fine (connecting to pitt, locally), and was able to get the XML document (IIS Log showed proper credential was  passed). However if you take a look closely, you can see first 2 attempts  failed (401 error), however 3rd time the credential was passed (alpha/rini):

2. Web Part  running locally, gets 401 error (On the IIS Log, the Credential was NOT even being passed, it was  missing from the Http Request!!!!)

Problem Isolation

To isolate the problem, I wrote a very simple Windows .NET application.

Extremely Strange:

When Windows Application ran locally, get 401 Access Denied error:

When Windows Application ran  remotely from another computer on the LAN, it worked ???

Workaround

After spending so much time, I came up with a workaround:

1. Delete the HOST header on IIS for your MOSS web application

2. In the code, do not use the host name. Use “localhost” instead:

This works for both web part and windows application!

Final Solution

With help from the coworkers in our team to solve this weird problem,  no one had a clue why this was happening.  Finally one of our team members recalled that there was similar authentication issue on production server a while ago and our Operation group changed one registry and fixed it. This lead us to a new keyword, called “Registry”.  Google on this important  keyword,  BINGO!  Found the Microsoft article: http://support.microsoft.com/kb/896861

Following the article and edited the registry, and it FIXED the problem!!!!

Further reading the article, this explains why my workaround worked, because HOST NAME did not match with the MACHINE NAME!  It was a new security feature being introducted in Windows 2003 Service Pack !!  Damn it.