Resend Request

Request retransmission of messages when a sequence gap is detected

FIXsession: admin35=2

The Resend Request message (35=2) is sent by either party when a sequence number gap is detected — that is, when an incoming message has a sequence number higher than expected. It requests the counterparty to retransmit all messages in the gap range.

Upon receiving a Resend Request, the counterparty should respond with either:

• The original messages with PossDupFlag (43) = Y, or
• A Sequence Reset with GapFillFlag (123) = Y to skip messages that are no longer available (e.g. administrative messages).

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Fields

header · required

35=2

7 - BeginSeqNo · integer · required

First message sequence number to be retransmitted.

16 - EndSeqNo · integer · required

Last message sequence number to be retransmitted. Use 0 to request all messages from BeginSeqNo onwards (i.e. up to the current sequence).

trailer · required

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Sequence Reset — Gap Fill

When a Resend Request is received, respond with a Sequence Reset using GapFillFlag (123) = Y and NewSeqNo (36) set to the sequence number after the gap. This tells the server the client is skipping over the requested range rather than replaying it.

Resend Request (server → client)

8=FIX.4.4|9=58|35=2|34=114|49=KRAKEN-MD|56=damien|52=20260407-20:23:52.000|7=8|16=0|10=142|

When to expect a Resend Request: If your client reconnects to an existing session without resetting sequence numbers (141=N), or if a message is dropped in transit, the server will send a Resend Request for the missing range. Always be prepared to handle it.