Ssis6 Upd ⇒

SSIS6 UPD — Comprehensive Overview

Re-evaluate Data Flow buffer settings (DefaultBufferMaxRows/Size).
Confirm parallelism settings (MaxConcurrentExecutables) align with updated behavior.
Recompile and redeploy packages that use Script Tasks (ensures they pick up patched assemblies).
Update connection drivers (OLE DB/ODBC) if connector-related fixes were included.

If you see ssis6 upd in a package but deploy to SQL Server 2014 (v5 runtime), you get:

Error: The package format version 6 is not supported by this version of SSIS.

Solution: Downgrade (not possible natively) or keep source package in v5. ssis6 upd

Not set on all upgrades – If using dtutil /copy without /upgrade, flag may be missing.
Can be faked – Manually edit VersionComments to ssis6 upd → runtime still checks internal checksum → fails validation.
SSIS 2017+ uses version 8, but some packages carry ssis6 upd as legacy comment after multiple upgrades.
No official removal – ssis6 upd stays forever once set; doesn't affect execution after successful format conversion.

Stability fixes: Resolved crashes and memory leaks in the SSIS runtime and Data Flow engine.
Catalog and deployment: Reliability improvements for project deployment to the SSISDB catalog and fixes for package versioning.
Performance optimizations: Improvements to buffer management and parallelism in Data Flow tasks that reduce CPU and memory pressure.
Connector updates: Bug fixes and enhancements for common connectors (OLE DB, ADO.NET, ODBC, Azure/Cloud connectors).
Designer/IDE fixes: Better behavior in Visual Studio integration—improved package validation, breakpoint handling, and package configuration UX.
Security patches: Addressed vulnerabilities in service endpoints and package storage handling.