You cannot jump directly from 6.1 to the latest version without risk. The recommended path is to save the code in LabVIEW 7.1 2018 or later Broken Functions:
: You can install multiple versions of the LabVIEW RTE on one machine if they have different major version numbers. System Requirements (6.1 Typical) Requirement Recommended RAM Disk Space 300 MB (Full) OS Windows NT 4.0 SP3+ / 98 / Me / 2000 / XP Windows XP Where to Find & Install Solved: LabView runtime engine 6.1 needed - NI Community
: Provides the core libraries and engine required to run stand-alone applications built with the LabVIEW 6.1 Application Builder Web Integration