Quartararo was battling for second with Aprilia’s Aleix Espargaro when he lost the front-end of his Yamaha while overtaking the Spaniard at the Turn 5 hairpin on lap five of 26.
The Yamaha rider remounted dead last with a damaged bike, while Espargaro lost 8.1s as he recovered through the gravel before going on to snatch fourth on the final lap with a last-corner overtake on Brad Binder and Jack Miller.
Quartararo came into the pits on lap nine before returning to the circuit, but would crash again when he highsided exiting Turn 5 three laps later.
It marked the world champion’s first race retirement since Portugal last year and has seen his points lead cut from 34 to 21 going into the summer break.
Speaking to Canal+ after the race, Quartararo blasted his “stupid mistake” and says he restarted the race because his team told him to in case there was rain and a bike swap was required.
“I made a rookie mistake, I wanted to push too much from the beginning,” Quartararo said. “It's with these mistakes that you learn for the future, but it was a really stupid mistake.
“We could very well have set a very good pace and fought for the win. These are mistakes that you learn from for the future.
“I wanted to restart and try to score some points but I saw that the bike was a problem. I stopped, the team told me to restart in case of rain but when I restarted I could see that something was wrong.
“I tried but I don't know, we have to analyse the crash but I lost the rear a bit abruptly, so we'll see what they say. I made a rookie mistake.”
Quartararo, who went to apologise to Espargaro after the race, also said the Aprilia rider should have been “the winner” today given the pace he had.
When asked why he went to Espargaro’s garage, he said: "To apologise, because the winner today was him because of the pace he had.
“Just to apologise for my mistake. He rode a very good race.
“We made a mistake at this track but our potential is there so I hope for the same as in the previous races. We'll see.”
