There are sequences in ISO-8859-1 that will cause UTF8 application to balk if they are read without conversion - sometimes in a part that is well away from the

There are sequences in ISO-8859-1 that will cause UTF8 application to balk if they are read without conversion - sometimes in a part that is well away from the input itself. A common example "órny", part of a number of Polish place and personal names. ISO 8859-1 (and -2, and others) form would be F3 72 6E 79. UTF-8 treats F3 as a start of a 4 byte sequence where each subsequent character is in 80 - BF range (as specified in RFC 3629): UTF8-4 = %xF0 %x90-BF 2( UTF8-tail ) / %xF1-F3 3( UTF8-tail ) / %xF4 %x80-8F 2( UTF8-tail ) UTF8-tail = %x80-BF This nicely causes an exception in both Java and Python, for instance, if they were to do what Go does here - and there is nothing anyone from adding an X- header to the request or response to try just that.