104 posts

Fix ASP.NET Core application HTTP Error 500.30 ANCM In-Process Start Failure

Last week when I was working on an ASP.NET Core web application, suddenly I got an error like this: The common causes listed in the error message are quite vague and not very helpful. But fortunately, the link in the error message above to Microsoft’s documentation site provides some guidance on how to fix the error. I have to admit that the troubleshooting information in the error message or on Microsoft documentation site does not […]

Identifier is null or empty error when adding stored procedure in entity framework data model

You can add database tables and stored procedures in your Entity Framework data model, but you may encounter an ArgumentException error in Visual Studio when adding a stored procedure: An exception of type ‘System.ArgumentException’ occurred while attempting to update from the database. The exception message is: ‘Identifier is null or empty’ The error message is confusing because the actual cause of this error is that the stored procedure does not have a return value. In […]

Session Cookie Does Not Contain the “Secure” Attribute

Recently we scanned one of our web applications by two famous source code analysis tools: Qualy’s Web Application Scanning tool and HPE’s Fortify Static Code Analyzer, but the results are different. Qualy’s WAS picked up one XSS security vulnerability and two information disclosure warnings, but HPE’s Fortify didn’t find anything vulnerable. It would be interesting to find out why, but I am not gonna cover that today. Today I would like to talk about one […]

You must manually configure this site for ASP.NET 4.5 in order for the site to run correctly

Recently I got a new Windows 10 computer at work and tried to open an Visual Studio 2010 project, and then I got a web server error as follows: Configuring Web http://localhost:64886/ for ASP.NET 4.5 failed. You must manually configure this site for ASP.NET 4.5 in order for the site to run correctly. ASP.NET 4.0 has not been registered on the Web server. You need to manually configure your Web server for ASP.NET 4.0 in […]

WCF service WSDL shows wrong URL address when using HTTPS

Recently I developed a WCF Web service and deployed it to a server with SSL, however, when clients try to add the service reference in their Visual Studio IDE, the endpoint URL address generated in the web.config or app.config file points to a wrong URL address: it points to the internal machine name instead of the production URL address. Because our SSL certificate is registered with the production URL, this wrong endpoint URL address causes the security […]

How to fix SharePoint query error-cannot complete this action please try again

This SharePoint query error kept me busy for a while because the error message is very generic and useless, so I hope my experience can help someone in the future. When I ran my ASP.NET application to query a specific resource item from a SharePoint list the other day, I got this error message: Cannot complete this action. Please try again. You can see that this error is very generic and it didn’t provide much […]


Recently a support ticket was sent to me regarding an error customers get while trying to download a file with Google Chrome browser, and the error is ERR_RESPONSE_HEADERS_MULTIPLE_CONTENT_DISPOSITION as shown below: And this error only happens in Google Chrome browser, users of IE, FireFox, and Safari all can successfully download the file. After some further investigation, it turned out that the root cause was that the filename of the uploaded file contains a comma “,”. […]

How to find the internal field names for SharePoint list columns

When you develop applications that interact with SharePoint lists, you may come to a point that you need to retrieve value from each column of a list by referencing the name of the list coluumn, however, you may end up with an error saying the column does no exist. This is because the name you use to create a column in SharePoint may not be the same as the one stored in SharePoint (which is […]

[Solved] Cannot have multiple items selected in a DropDownList

If you work on ASP.NET DropDownList, most likely you will encounter a situation when you need to pre-select an item in the DropDownList. You might see people using the following way to do that after the DropDownList is bound: this.ddlSchools.SelectedValue = oSchool.AdminID This works very well if you are sure that the value you assign to the DropDownList actually is one of the DropDownList items, otherwise, you will get an ArgumentOutOfRangeException. So the safe way to […]

Retrieving the COM class factory for component with CLSID failed due to the following error

First of all, as .NET developer, you should NOT use COM components in your .NET applications any more, because it is old and unmanaged. The detailed error message usually looks like this:  Retrieving the COM class factory for component with CLSID {000209FF-0000-0000-C000-000000000046} failed due to the following error: 800xxxxx The error code may be different, but the cause of the error is usually the same. The most common cause of the error is that most […]