PRB: ASP.NET Web Application Exceeds Maximum Number of Supported Connections Under a Single-User Scenario (320072)


The information in this article applies to:

  • Microsoft ASP.NET (included with the .NET Framework 1.1), when used with:
    • the operating system: Microsoft Windows XP
    • the operating system: Microsoft Windows 2000
  • Microsoft ASP.NET (included with the .NET Framework) 1.0, when used with:
    • the operating system: Microsoft Windows XP
    • the operating system: Microsoft Windows 2000
This article was previously published under Q320072

SYMPTOMS

When you develop ASP.NET Web applications on a computer that is running Microsoft Windows 2000 Professional or Microsoft Windows XP Professional, if that computer serves as the local Web server, the maximum supported connections are exceeded when you open the application locally in a single-user scenario.

You receive an error message that states that the server or the host is unavailable. For example, you may receive the following error message in your browser:
The page cannot be displayed
There are too many people accessing the Web site at this time.

HTTP 403.9 - Access Forbidden: Too many users are connected Internet Information Services
When you use Microsoft Internet Security and Acceleration (ISA) Server, you may receive the following error message in your browser:
64 - Host not available Internet Security and Acceleration Server

CAUSE

This problem occurs when you open the page because the proxy server holds onto connections under the following conditions:
  • You specify the network basic input/output system (NetBIOS) name of the local Web server in the URL.
  • You configure the browser to use a proxy server.
  • You do not select the Automatically Detect Settings and the Bypass proxy server for local addresses check boxes in the Local Area Network (LAN) Settings dialog box.
When the proxy server holds onto connections, the connections exceed the number of connections that are supported.

RESOLUTION

To resolve this problem, click to select the Bypass proxy server for local addresses check box when you develop ASP.NET Web applications on a local Web server. As a result, the proxy server does not have to be involved when you open the application that is served up by the local Web server.

You can also use localhost in the URL instead of the NetBIOS name of the local computer when you open the application locally. However, you must still click to select the Bypass proxy server for local addresses check box. If you do not select this check box, you may receive an "HTTP Error 502: Proxy Error" error message.

STATUS

This behavior is by design.

MORE INFORMATION

Steps to Reproduce the Behavior

  1. Follow these steps to create a new ASP.NET Web application:
    1. Start Microsoft Visual Studio .NET.
    2. On the File menu, point to New, and then click Project.
    3. Click Visual C# Projects or Visual Basic Projects under Project Types, and then click ASP.NET Web Application under Templates.
    4. In the Location box, replace the default WebApplication# name with MyWebApp. For example, if specify the local Web server as "http://local computer," the Location box appears as follows:

      http://local computer/MyWebApp

  2. Follow these steps to add a new Web Form to your project:
    1. In Solution Explorer, right-click the project node, point to Add, and then click Add Web Form.
    2. In the Name box, type SamplePage.aspx, and then click Open.
    3. Drag an ASP.NET Button server control from the Web Forms section of the toolbox to the page.
    4. On the File menu, click Save All to save the Web Form and other files that are associated with the project.
    5. On the Build menu in the Visual Studio .NET integrated development environment (IDE), click Build Solution.
  3. Follow these steps to configure the connection settings in your browser:
    1. On the Tools menu in the Visual Studio .NET IDE, click Options.
    2. Expand the Projects node in the options tree, and then click Web Settings.
    3. In the Web Server Connection area, click Connection Settings.
    4. In the Internet Properties dialog box, click LAN Settings.
    5. In the Local Area Network (LAN) Settings dialog box, click to clear the Bypass proxy server for local addresses check box.
    6. If Auto Discovery is enabled on the proxy server, and if Web Proxy AutoDiscovery (WPAD) is supported, click to clear the Automatically Detect Settings check box.
  4. In Solution Explorer, right-click the .aspx page, and then click View in Browser.
  5. Click the button on the page repeatedly to make the page post back to the server. After you click the button ten times, you receive an error message that states that the host or the server is unavailable.

REFERENCES

For additional information about the simultaneous user connection support that is associated with running Microsoft Internet Information Services (IIS) on Windows 2000 Professional and on Windows XP Professional, click the article numbers below to view the articles in the Microsoft Knowledge Base:

262635 Error Message: HTTP 403.9 - Access Forbidden: Too Many Users Are Connected

318380 IIS Status Codes

Modification Type:MajorLast Reviewed:8/12/2003
Keywords:kbprb kbServer KB320072 kbAudDeveloper
©2003 Microsoft Corporation. All rights reserved.