string.Contains() and IndexOf() throw FormatException

Question

Why would myString.Contains(" ") or myString.IndexOf(' ') throw a FormatException "Invalid name format"? This exception is only thrown when there is a space in myString.

Answer 1

Looking at the MSDN pages for the string.Contains and string.IndexOf methods clearly shows that neither of these methods ever throws a FormatException.

I can only conclude that it must be another part of the code (possibly a call to string.Format?) throwing this exception. Perhaps posting the relevant section of code would help?