Taken together, "SSIS6 UPD" most plausibly denotes an update/patch (UPD) for a versioned SSIS product or an internal release named “SSIS6.” Below is a comprehensive, well-structured explanation covering possible meanings, typical contents, installation guidance, troubleshooting, and best practices.
Package runs fine in SSDT (VS 2015), fails in production SQL Agent (SQL 2016) with: ssis6 upd
For bulk upgrades, use dtutil.exe (SSIS package utility): Taken together, "SSIS6 UPD" most plausibly denotes an