The System.Text.DecoderFallback object represents an error handler that is invoked when an encoded byte sequence cannot be decoded into a character. Any one of the following handler types is supported:

• A best-fit fallback handler, which replaces bytes that cannot be decoded with some suitable replacement character.

• A replacement fallback handler, which replaces bytes that cannot be decoded with some arbitrary replacement character. The .NET Framework includes one replacement fallback handler, System.Text.DecoderFallback, which by default replaces bytes that cannot be decoded with a question mark ("?") character.

• An exception fallback handler, which throws an exception when bytes cannot be decoded. The .NET Framework includes one exception fallback handler, System.Text.DecoderExceptionFallback, which throws a System.Text.DecoderFallbackException when bytes cannot be decoded.