The content length was computed incorrectly

[cat101]

I found that in certain conditions, the server would respond before the last CRLF was sent and then when the arduino tried put write it would receive a connection reset

[fnevgeny]

FWIW, it's off by 4 bytes, not 1 - two CRLF's are sent after the body. And both are extraneous IMO, see https://www.w3.org/Protocols/rfc2616/rfc2616-sec4.html : "[...] an HTTP/1.1 client MUST NOT preface or follow a request with an extra CRLF".