Question

I have an application which tries to load some expected registry settings within its constructor.

What is the most appropriate .NET Exception from the BCL to throw if these (essential, non-defaultable) registry settings cannot be loaded?

For example:

 RegistryKey registryKey = Registry.LocalMachine.OpenSubkey('HKLM\Foo\Bar\Baz');   // registryKey might be null!  if (registryKey == null)  {      // What exception to throw?      throw new ???Exception('Could not load settings from HKLM\foo\bar\baz.');  } 

Answer 1

I’d go with ArgumentException or ArgumentOutOfRangeException..

throw new ArgumentException('Could not find registry key: ' + theKey); 

Quoting MSDN:

The exception that is thrown when one of the arguments provided to a method is not valid.

…

IMO writing a proper exception message is more important.