The United States end the negotiations with France during the XYZ Affair because French officials demanded that the United States pay bribes.
The XYZ Affair was an incident in 1978, involving US envoys to France and un-named French diplomats who identified themselves as X, Y, and Z. They demanded substantial bribes and payments from the US envoys in exchange for ceasing of French hostility to US merchant ships as a result of the US entrance into the Jay treaty with Great Britain.