FIX Sequence Reset Required – How to Recover
Sequence reset is required when message sequence numbers (MsgSeqNum, tag 34) become out of sync between client and broker. This can happen after disconnections, application restarts, or sequence number corruption.
Root Cause
1) Application restart without sequence persistence, 2) Sequence numbers not synchronized after disconnect, 3) Manual sequence reset not coordinated, 4) Sequence corruption, 5) Gap fill failed requiring reset.
Broker/Exchange Action
Broker may send SequenceReset (35=4) with ResetSeqNumFlag=Y and NewSeqNo to reset sequence, or request client to reset during logon.
Client/Your Action
1) Persist sequence numbers to disk, 2) Recover sequence on restart, 3) Coordinate sequence reset with broker, 4) Send SequenceReset with NewSeqNo=1 if resetting, 5) Ensure both parties reset together.
Example FIX Message
How FIX Doctor Detects This
FIX Doctor detects sequence gaps and flags when ResetSeqNumFlag is set incorrectly. Timeline shows sequence reset events.
Related Errors
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