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Improved

OSL FIX - September 2026 Release

8 days ago

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Release Overview

This update transitions the FIX service to a high-availability active-active architecture, upgrades security configurations, resolves critical order/login bugs, and updates the sequence number reset behavior. There are no changes to FIX message specifications, fields, or protocol behavior.

Client-Facing Changes

  • Sequence Number Reset Logic: Removed the fixed daily morning reset. MsgSeqNum will now automatically reset only after reaching 2,500,000 (approximately once per week for high-frequency traders).

Infrastructure & Security Enhancements

  • Active-active Architecture: Upgraded FIX services to active multi-master nodes to support concurrent active traffic handling and improved fault tolerance.
  • Database Configuration: Improve configuration with dynamic database-driven configurations.
    Bug Fixes & System Stability
  • Infinite Login Loop Fix: Resolved a production bug causing clients to repeatedly re-login when encountering MsgSeqNum too low errors.
  • Order Amendment Deadlocks: Fixed a deadlock condition during order modifications.
  • Legacy Order Amend Compatibility: Restored compatibility for legacy engine order amendments carrying previous order IDs.

Action Required

No code or FIX message format changes are required. However, clients need to make the following operational adjustments:

  • Update Sequence Reset Automation: Clients with automated workflows or end-of-day scripts that rely on a mandatory daily morning sequence reset (MsgSeqNum) must update or disable those scripts. Systems should be prepared for sequence numbers to persist across days until reaching 50,000,000.
  • Optional Testing (Order Amendments): If clients plan to utilize the updated order modification/amend flows (carrying legacy order IDs), testing in the staging/UAT environment is recommended before sending live amendments.

Testing

  • The change has been deployed to the sandbox environment and is ready for testing.
  • Conformance / reconformance is not required for this upgrade.

Schedule

Production release TBC. Please subscribe to https://status.osl.com/ for updates.

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