This message is generated when the positions specified in the third argument of StringReplacePart fall outside of the string given in the first argument.
Off[message] switches off the message; On[message] switches it on. For example: Off[StringReplacePart::repart].
Examples
Basic Examples(1)
An error occurs because the specified string positions are not available in the string given in the first argument:
This shows a valid position specification for the given string: