Posts and information related to ASP.NET, .NET Core, ASP.NET Core and the .NET Framework

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An System.Collections.Generic.KeyNotFoundException “The given key was not present in the dictionary” can be the result of using a too old MySQL Connector/NET version in your ASP.NET web application. A KeyNotFoundException is thrown when an operation attempts to retrieve an element from a collection using a key that does not exist in that collection. An unsupported character set like utf8mb4 can be such a key, if your Connector/NET doesn’t support this character set. Luckily there is an easy workaround for this.

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A connection string is sometimes a bit obscure. Do I need ODBC or OLE DB? When you need one and Google for it, you often find old ones that either don’t work at all anymore, or are not optimal. This article provides you with a couple of ASP.NET to SQL Server connection string examples, and as a bonus for ASP to MySQL too.

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Whenever you need to test your ASP.NET connection to your MySQL database, using ODBC, you can use the following C# test script. Currently it uses MySQL ODBC 8.0 Unicode Driver, but you can easily change the version used. As a bonus it prints some connection information and it requires an SSL connection to your MySQL database (SslMode=REQUIRED).

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Users can install and run multiple versions of the .NET Framework on their computers. When you develop or deploy your app, you might need to know which .NET Framework versions are installed on the user’s computer.

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Remove HTTP response headers in IIS 7, 7.5, 8.0, 8.5, 10 and ASP.NET

Windows Server IIS loves to tell the world that a website runs on IIS. It does so with the Server header in the HTTP response, as shown below. In this post I’ll show you how to remove response server headers in IIS. You don’t want to give hackers too much information about your servers, heh? ;-).

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Simple MySQL connection test from your website with ASP.NET, PHP & classic ASP. Whenever you need a MySQL connectivity test from a website or server, it’s handy to have various test scripts nearby. Whether it is because you are setting up a new website or you have just installed a new server and are running your tests.

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Umbraco Project Belle

Configure Umbraco for SQLServer sessionState storage, for your sessions. This post explains how to prepare your Umbraco website for a high performance web garden or web farm, and load balancing environments: Store your ASP.NET / Umbraco sessions out-of-process (OutProc). As opposed to the default in-process (inProc) sessions, where sessions are saved in the worker process.

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How to add custom headers to System.Net.Mail? When sending an email using the MailMessage class (System.Net.Mail namespace) in an ASP.NET website, certain email headers like Message-ID are not always set. When a Message-ID header is missing, email might be blocked by the recipients SMTP server. Therefore it is necessary to set such headers…

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How to target multiple ASP.NET versions with AppCmd?

When administering an IIS web server you frequently have to use AppCmd.exe to make configuration changes. Whether it is for a specific web site or server wide. Some think AppCmd is very limited: if you don’t know the options to use, you may think you can only address the x64 .NET Framework version, or only x86, or you can only target the current active .NET Framework version. Fortunately this is not true, you can address both x86 and x64 versions of .NET with AppCmd. Read how…

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Today one of our clients received a System.Net.WebException error on a newly deployed ASP.NET web application. Part of the exception was: “System.Net.WebException: The underlying connection was closed: Could not establish trust relationship for the SSL/TLS secure channel.“. Here is how we resolved that issue.

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(ASP).NET programmers have to keep certain rules in mind when developing high performance ASP.NET applications, and/or optimizing your existing ASP.NET website. A lot of information is available on this subject. In this post I’ll share some valuable posts, and I continue to update this post when I find something new. Posts about ASP.NET performance I frequently pass on to customers so they can improve their ASP.NET web applications.

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Send authenticated SMTP (auth-SMTP) over a TLS encrypted connection. If you want to send email securely from your website, this post is for you! In this post I’ll provide some script examples for ASP, PHP, and ASP.NET (C# / VB.Net) that you can easily integrate in your website.

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Multiple vulnerabilities found in IIS 6.0 and 7.5 web servers. On the Full-Disclosure mailinglist Kingcope posted several IIS 6.0 and 7.5 bugs. Because I am a Windows Server and IIS admin, I took some time to test the various vulnerabilities …

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If you forgot your Umbraco admin password, use the following SQL query to reset your Umbraco admin password in SQL Server Management Studio (SSMS) or MySQL…

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