Following tutorial provides an example to run a single instance of WinForms application using Mutex. There are multiple ways to achieve the same result but this is kind of neat solution in my opinion. Add following SingleInstance class in your project. Here is how to use it in Program.cs > Main function
If the Uri is “mailto”, the Uri format must be in the following format. I encountered following error It was difficult to find the root cause. Finally I found that I used “&subject” (ampersand) for the first parameter instead of “?subject” (question mark). Once I used “?subject”, everything worked as expected.
If you are an Object Oriented programmer, here is explanation that will help you visualize the difference between .NET Standard, .NET Core and .Net Full Framework. Even though technically not correct, it will help you understand various online articles.