exception

CA2208: Instantiate argument exceptions correctly

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The CA2208 code analysis rule checks for common mistakes when constructing argument exceptions. There are three main argument exception classes: ArgumentException, ArgumentNullException, and ArgumentOutOfRangeException. Unfortunately, it’s easy to make a mistake when using these. I’ll explain the common mistakes that CA2208 checks for and how to fix them (and when to suppress the warning instead). … Read more

C# – Hide a method from the stack trace

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When you want to exclude a method from showing up in the stack trace, you can apply the StackTraceHidden attribute to the method: Note: This attribute was added in .NET 6. You can apply StackTraceHidden to a class to hide all of its methods from the stack trace: Use StackTraceHidden with throw helper methods StackTraceHidden … Read more

C# – Global exception event handlers

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There are two global exception events available in all .NET applications: You wire up these event handlers in Main() (before anything else has executed), like this: Note: If you’re using top-level statements, put these statements at the top of the ‘entry point’ file. This outputs the following before crashing: Notice the FirstChanceException event fired first. … Read more

Control ASP.NET behavior when background service crashes

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When a background service throws an unhandled exception in ExecuteAsync(), you have two options: You can change the behavior if the default isn’t what you want (notice the default behavior changed in .NET 6). In .NET 6+, you can configure the behavior in the initialization code. Here’s an example of making it ignore crashed background … Read more

C# – Try/finally with no catch block

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Try/finally blocks are useful for when you are required to do something at the end of a method no matter what. The finally block always executes, even if there’s an exception (there is one case where this isn’t true, which I’ll explain in the Unhandled exception section below). There are a few common scenarios where … Read more

C# – How to create a custom exception

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To create a custom exception, create a subclass of the Exception class, like this: Then throw it just like you would any other exception, like this: It’s a good idea to call the base constructor from your constructor and pass in your custom error message. If this exception is unhandled, or if you are logging … Read more

System.BadImageFormatException: Could not load file or assembly

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Problem – Can’t load assembly When you have one assembly trying to use another assembly, and they don’t have matching bitness (x64 or x86), then you’ll get an exception: either BadImageFormatException or FileLoadException. If your project references another assembly, and the bitness doesn’t match, you’ll get this exception: System.BadImageFormatException: ‘Could not load file or assembly … Read more

C# – Conditionally catch exceptions with filtering

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You can use exception filtering to conditionally catch exceptions, like this: Note: This feature was added in C# 6. Any SqlException that doesn’t meet the condition specified in the when clause will not be caught. Previously, without exception filtering, you’d have to handle that scenario in the catch block and rethrow, like this: Exception filtering … Read more