Bugs related to a new software system, which includes over-the-air updates, are said to be responsible for the late launch.
Stackmann also confirmed earlier reports the Mark VIII Golf was delayed due to bugs in its software, with the brand chief nominating the new over-the-air system update system as the primary cause.
"Due to their online connectivity there is a lot more software especially in the area of security, which is a real challenge since the car is no longer a closed ecosystem," Stackmann told the industry journal.
He also noted over-the-air updates complicates the homologation process as it allows companies to add new and potentially unforeseen features to car after it has been certified.
The company says it is working with type approval authorities.
Volkswagen originally planned to launch the eighth-generation Golf at the Frankfurt motor show in September this year.
Volkswagen Australia says the new Golf is still on track to be launched in Australia during the third quarter of 2020.