fix protocol - Quickfix Syncing Sequence Numbers

Question

If, for whatever reason, my application loses track of what sequence number I was on, what is the recommended way of re-establishing the session to continue trading?

Answer 1

From FIX 4.1 onwards, the Logon message (A) contains a tag ResetSeqNumFlag (141). Setting it to 'Y' "indicates that both sides of the FIX session should reset sequence numbers."