Lynn was battling with McLaren protege Stoffel Vandoorne and Rapax driver Sirotkin into the first chicane, when he attempted a move on the inside.
He misjudged the braking zone and collided with the helpless Sirotkin, leaving both of them with race-ending damage.
DAMS driver Lynn was handed a five-place grid penalty for the collision but will start from the pitlane as he cannot serve the full demotion having only been 21st on the 25-car grid.
Vandoorne: I had to dominate GP2
Lynn accepted full responsibility for the incident.
"Obviously it was my fault," he told AUTOSPORT.
"It's a real shame because obviously I just passed Stoffel.
"The problem was I think it was the first time I arrived with DRS on the pit straight and I braked too late and didn't make the corner.
"Unfortunately Sergey was right in the middle of the corner and couldn't avoid the contact which was a shame, because it ended what was a good race for me and obviously took him out, which isn't fair.
"Luckily the only thing I've got is a bruised ego and I live to fight another day."
Lynn was in contention for the race win at the time, running ahead of eventual victor Alexander Rossi after the frontrunners had pitted.
Vandoorne seals GP2 title in Russia
Rossi wins after Lynn crashes out