A loose drain cover cost teams a significant amount of running time in the first session of testing on Thursday, curtailing the running nearly two hours early.
The stoppage quickly became a protracted one, although it wasn't initially clear what had caused the red flags to be waved.
In the event, a drain cover had come loose at Turn 11, with Charles Leclerc and Lewis Hamilton both running over it - dislodging and demolishing the cover, with Leclerc appearing to pick up some damage.
There was also concern at Mercedes, as a piece of Hamilton car was seen flying off at turn one as he was passing McLaren's Oscar Piastri.
Officials began a track inspection to resolve the issue, while Ferrari and Mercedes started inspections of their own as they assessed the damage done to their cars.
Ferrari closed their shutters before re-opening, suggesting that they had taken the floor off of the car but that progress had been made to resolve the problem.
After more than 30 minutes of inspection, the session was cancelled amid track repairs and the hour-long lunch break has been moved forward, meaning the drivers will now run for five hours in the afternoon session.