Network Gurus: Advice please! These packets yielded "Invalid POST Request"

The identical Save operation sometimes succeeds and sometimes fails in our web app. I did it many times with the same document. It worked about 75% and errored about 25%.

Our Domino server is logging “Invalid POST Request Exception” sometimes, in one application. (It gives the user an Error 500 page when it happens.) User is on Internet Exploder 6.00.2800.1106, server runs R6.5.3 on Windows Server 2003.

I was advised to analyze the packet stream. Using “ethereal” I captured the packets in a successful save and in a failed one. I hope somebody can offer ideas about what is going wrong here and what components need attantion.

When it failed, the order of events was:

4:02:14 PM: Trying to POST:

–Client sends “POST” packet to server

–Client sends 4 “Data” packets to server

–Client receives “ACK” packet (for “POST” packet) from server.

4:02:15 PM: Re-transmitting

–Client retransmits 1st “Data” Packet

4:02:17 PM:

–Client retransmits 1st “Data” Packet

4:02:21 PM:

–Client retransmits 1st “Data” Packet

4:02:29 PM:

–Client retransmits 1st “Data” Packet

4:02:45 PM:

–Client retransmits 1st “Data” Packet

4:03:17: Client requests, gets new connection:

–Client sends “SYN” packet to server

–Client receives “SYN ACK” packet from server.

–Client sends “ACK” packet to server

     Client POSTS again:

–Client sends “POST” packet to server

–Client receives “ACK” packet (for “POST” packet) from server.

–Client receives “ACK” packet from server which is a “TCP window update” packet.

4:03:32: Server declares a foul:

–Client receives “HTTP 1.1/500 Internal Server Error” packet from server.

–Client sends “ACK” packet to server for “HTTP 1.1/500” packet

 Client and server close connection:

–Client receives “FIN / ACK” packet from server.

–Client sends “ACK” packet to server

–Client sends “FIN / ACK” packet to server

–Client receives “ACK” packet from server.

Do I blame the network? the Domino Server? IE? Windows? The IETF? What should I do next?

Subject: Network Gurus: Advice please! These packets yielded “Invalid POST Request”

Check the Fix List database. I believe that 6.5.4 fixes a regression introduced somewhere in 6.x (maybe even 6.5.3?) regarding invalid POST requests… something related to File Upload controls if I recall.

Subject: Network Gurus: What is “Invalid Character Set”?

Many Thanks! We are indeed on 6.5.3, and we do have an upload control on the page.

The SPR says it causes an “invalid character set”. Is that a flaw in the POST that the browser sends?