More than 10,000 trainee secondary teachers will have to retake their qualifying examination because of a rail breakdown near Paris.
Holdups on a suburban railway line delayed many of the 1,100 candidates due to take their certificat d'aptitude professionnelle a l'enseignement secondaire in history and geography at the regional centre outside the capital.
Officials postponed starting the exam by an hour, but about 100 students still arrived too late. Finding themselves excluded they shouted and banged on the windows, leading to disruption inside and the eventual abandonment of the exam.
The French education ministry has fixed a date for a resit, but regulations specify that all candidates must take the national exam simultaneously. Now all 10,100 history-geography entrants in the country will have to sit it again.
Furious provincial students protested, in some areas burning their new exam notices outside education authorities' offices. Recriminations have broken out over the handling of the situation by officials and over the behaviour of candidates.
This is the second year running that history-geography students have had to resit the exam - in 2001 about 100 papers were stolen. Students who repeated a year after failing last year will have had to take the exam four times altogether.