Excel process not closing [duplicate]

Answer 1

Here is an interesting knowledge base on the subject of office apps staying open after a .NET app disconnects from them.

Office application does not quit after automation from Visual Studio .NET client

The code examples are all in the link (vb.net sorry). Basically it shows you how to correctly setup and tear down the office app so that it closes when you're finished with it.

System.Runtime.InteropServices.Marshal.FinalReleaseComObject is where the magic happens.

EDIT: You need to call the FinalReleaseComObject for each excel object that you've created.

if (excelWorkSheet1 != null)
{
    Marshal.FinalReleaseComObject(excelWorkSheet1);
    excelWorkSheet1 = null;
}
if (excelWorkbook != null)
{
    Marshal.FinalReleaseComObject(excelWorkbook);
    excelWorkbook = null;
}
if (excelApp != null)
{
    Marshal.FinalReleaseComObject(excelApp);
    excelApp = null;
}