That's an error in your code. Look for an index out of range or rather, an int value that's overflowing or something like that (Note: I don't do C#, so I don't know exactly what this exception is. Though, I'd bet on the second one).

Note: don't raise issues for that kind of things, issues are used when the kata is dysfunctionning. But since already 300 users completed it in C#, the problem is more likely laying on your side. When you have troubles with a kata, ask rather for a "Question".

Cheers

System.ArgumentOutOfRangeException : Specified argument was out of the range of valid values.
Parameter name: count

What is it??

C#

Lol. Ok you can use your own quick sort, but what the reason, if the task is not implement your own quick sort?

I think that explanation in the comments must be in the instruction too :)

lol