Errors accessing Visual Studio Team System Web Access site with an underscore ("_") character in the name

Source: Microsoft Support

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You configure a server to host Visual Studio Team System Web Access. The site name contains an underscore character ("_"). You try to access the site using a web browser.

You may see different errors depending on how you access the Team System Web Access site. For example:

1. When you go to the Team System Web Access site, Internet Explorer displays an error saying “Internet Explorer cannot display this web page”. The error details might indicate a possible DNS or authentication issue.

FAILS: Team System Web Access on http://server_name:8090, Team Foundation Server on http://server_name:8080

2. Connecting to Team System Web Access using the IP address, but using the server name to connect from Team System Web Access to Team Foundation Server causes the following error message to be displayed on the Team System Web Access login form: "The request failed with HTTP status 405: Method Not Allowed."

FAILS: Team System Web Access on http://<IP Address>:8090, Team Foundation Server on http://server_name:8080

3. If IP addresses are used instead of the server names when connecting to both Team System Web Access and Team Foundation Server, everything works fine. In some cases, using a browser other than Internet Explorer might work fine using server names.

WORKS FINE: Team System Web Access on http://<IP Address>:8090, Team Foundation Server on http://<IP Address>:8080 

Analyzing the network traffic between the browser and Team System Web Access website shows that the browser is being redirected continuously between login.aspx and index.aspx until it gives up. The same behavior can also be observed by looking at the Team System Web Access log files, which look similar to:

... Creating TeamFoundation Server...
... TeamFoundation Server Successfully Created.
... Creating WorkItemStore...
... WorkItemStore Successfully created.
... Response is redirected to /index.aspx?pname=Project1.
... Session Started
... Response is redirected to /UI/Pages/Login.aspx?redirect=%2findex.aspx%3fpname%3dProject1.
... Session Started
... Creating TeamFoundation Server..

Underscore ("_") is not a valid character for URLs according to the RFCs (this is why you cannot register a domain name with an underscore).

When you use Internet Explorer against a web site that uses session cookies (such as Team System Web Access), a valid session cannot be established due to a security feature in Internet Explorer cookie handler if the server URL contains underscore characters.

Ideally, don’t use underscore characters in your server names. This issue is not specific to Team System Web Access, and you might end up with similar issues with different web applications that depend on session states.

For a quick workaround, you can connect to Team System Web Access using the IP address. You may also want to change the default Team Foundation Server entry in the Team System Web Access web.config to use the IP address of your Team Foundation Server, or "localhost" if Team System Web Access and Team Foundation Server are on the same machine.

For a longer term solution you should consider:

• Changing the name of your server to something that doesn't contain an underscore.
• Creating a DNS alias for your server that resolves to the same IP address, and use that name to connect to Team System Web Access and Team Foundation Server.

For more information on renaming a Team Foundation Server, please see:

How to: Rename an Application-Tier Server
http://msdn.microsoft.com/en-us/library/ms252469.aspx (http://msdn.microsoft.com/en-us/library/ms252469.aspx)

How to: Rename a Data-Tier Server
http://msdn.microsoft.com/en-us/library/ms253106.aspx (http://msdn.microsoft.com/en-us/library/ms253106.aspx)

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