There's no secret that at Monza top speed is everything. No one would therefore be surprised to know all the drivers are always looking for a tow for their qualifying laps.
What seems a reasonable strategy call got way out of hand way too quickly: after one lap only the situation blasted into chaos: "we have to stay behind Armstrong" - "Yeah but he's too slow!" engineers and drivers started screaming on the radios while mayhem started to take place.
For three laps in a row times were aborted when the leading driver stopped right before Parabolica, hoping to be overtaken and take some slipstream. Meanwhile behind him all 30 drivers jumped on their brakes and waited creating a massive traffic jam on the backstraight between the Ascari chicane and the last corner.
Having so many cars in such a small gap created many dangerous situations, in particular close misses between drivers warming up their tyres and others that tried to overtake the pack.

This 'ridiculous situation', quoting Lundgaard, forced the stewards to red flag the qualifyings and display the message: "Session will not restart".

For the starting grid, the order will follow the times set in the only lap that actually took place. The polesitter for the saturday's race will therefore be Lundgaard himself. The Danish driver will lead the pack in front of the Prema's trio of Armstrong, Shwartzman and Daruvala.

Half the grid in one shot 👀#ItalianGP 🇮🇹 #F3 pic.twitter.com/9akQGiYiX4

— Formula 3 (@FIAFormula3) September 6, 2019