There have been a number of councils held at Troyes:
Contents
Council of 867
The council was held on orders of Pope Nicholas I, to deal with Hincmar of Reims and his quarrels. The decrees were signed on 2 November 867. The Council ruled that no bishop could be deposed from his See without the consent of the Pope.
Council of 878 (Second Council of Troyes)
Council of 1078
Summoned By Archbishop Hugues de Die and the Abbot of Cluny.
Council of 1104
Convened by Cardinal Richard, Bishop of Albano, Papal Legate
Council of 1107
Convened on 23 May 1107 by Pope Paschal II personally. Rothard, Bishop of Mainz, was suspended from office because he had dared to reconcile a schismatic bishop, Udo of Hildesheim, to the Church.
Bishops attending
No complete list survives. Some bishops who probably attended can be discovered in surviving documents:
Council of 1129
References
Synods held at Troyes Wikipedia(Text) CC BY-SA