When the ASP.NET AJAX Functionality is not working on a web page, it is usually due to the fact that the javascript needed for AJAX is not sent to the client from the server for some reason. ‘Sys’ is undefined. You might see this error message when there...

Cross-posted from http://blogs.msdn.com/mike Enabling HTTP Compression for your IIS6 web applications is one way of increasing site performance. One of the more common problems I see when helping customers with compression is that their IIS servers...

A problem was seen where Internet Explorer clients would reset the TCP connection between them and the IIS server when they received an HTTP 200 response for static content from IIS. The problem manifests itself to end users as slow performance of the...

After sending an HTTP request to IIS, an Internet Explorer client displayed the following error message to the user: Bad Request Beginning in IIS 6.0, “Bad Request” errors are almost always returned by HTTP.sys, so the next step was to...

In this scenario, HTTP requests were being sent from a non-Windows machine and were being responded to with a “Bad Request – Invalid Hostname” error by the IIS server. Beginning in IIS 6.0, “Bad Request” errors are almost always returned by HTTP.sys,...

System Center Configuration Manager (SCCM) has a nice functionality of displaying report data as charts.  When deployed on a 64 bit IIS 6.0 machine these chart displays may stop working and you will start getting the following error message. This...

When hosting an ASP.net web application on IIS7, and you have the application running in integrated pipeline mode, you may find that users complain that the application performs slowly. This may occur if your website is busy, handling 12 or more requests...

If you implement custom health monitoring events in ASP.NET chances are that you should have worked with WebBaseEvent or WebErrorEvent classes and used the WebBaseEvent.Raise() method to fire those events. Recently an interesting issue related to this...

I was recently working on a reporting web application that uses the Report Viewer ( ReportViewer ) control that ships with SQL Server Reporting Services (SSRS). The Report Viewer control was rendering perfectly when I was developing using Visual Studio...

Thanks to Robert Patrick for submitting these issues There have been some issues recently where users complain of SSL connections suddenly no longer working with IIS7. Users can connect to IIS7 websites over http://, but browsing to https://...

This week I got an interesting issue altogether. One of my customers was unable to debug ASP.NET 3.5 application locally using Visual Studio 2008. The application was created using Web Application Project. When we started the application using "Start...