How to: Check if another instance of the application is already running

how it is possible to check whether another instance of the program is running and if so stop the application before loading if there is an existing instance of it.

Solution:

write at your Main method the following code to quit the method which will kill the currently loading process instantly.

if (System.Diagnostics.Process.GetProcessesByName(
 System.IO.Path.GetFileNameWithoutExtension(
  System.Reflection.Assembly.GetEntryAssembly().Location)).Length > 1)
 {
  MessageBox.Show("Application is already running");
  System.Diagnostics.Process.GetCurrentProcess().Kill();
 } 
            

How to: Close Windows form while doing CreateHandle()

The error Value Close() cannot be called while doing CreateHandle() usually happens when we try to close the form in the constructor or Load event.

For example,

the following code gives the error:

private void frmCustomer_Load(object sender, EventArgs e)
{
if (!Valid())
this.Close;
}

The Solution: