Roma had seemed on the verge of sending goalkeeper Robin Olsen to Lille for €5m plus bonuses, but talks have reportedly hit problems.
According to Sky Sport Italia, the negotiations had been down to the final details only for problems to emerge.
Now there is no guarantee that Olsen will wear the LOSC jersey this season, as the two clubs are struggling to work out the terms.
The Sweden international had just returned to the Stadio Olimpico after a loan spell with Everton in the Premier League.
He was meant to join Lille for €5m plus up to another €1m in bonuses.
The original idea was a loan with option to buy, but that was changed to a permanent transfer and a week ago it had seemed close to completion.
Roma already have a new goalkeeper to replace him, having signed Rui Patricio from Wolverhampton Wanderers.
Olsen has also been linked with a move to Atletico Madrid, where he would be the second choice shot-stopper.