Adrian was replaced as royal chancellor in 1188 at the latest, when
Saul Győr is mentioned in this capacity. By 1192, Adrian was elected bishop of Transylvania. According to a non-authentic charter, he held the dignity already in 1190. His last known predecessor in that office is
Paul, who is referred to as bishop in 1181. It is possible that Adrian became Bishop of Transylvania in 1187 or 1188, when Paul elevated into the position of
Archbishop of Kalocsa. Adrian was the bishop during that time, when the diocese was first called as "
Transylvanus", which name was preserved for centuries. His episcopal activity was completely covered by a jurisdictional conflict with the newly founded the
collegiate chapter of
Szeben (present-day Sibiu,
Romania). The "free" provostry was established by Béla III in 1189 with the intention to grant a separate church representation to the
Transylvanian Saxons, who gradually settled down in the southern part of
Transylvania since the reign of
Géza II.
Papal legate Gregorius de Sancto Apostolo, and later the
Roman Curia confirmed the foundation too in 1191. However, Adrian contested the jurisdiction of a certain "P.", the provost of Szeben over the territory of his diocese, who claimed that all South-Transylvanian Germans (
Flandrenses) were subordinated under his suzerainty. Upon the instruction of
Pope Celestine III, Gregorius recalled that when he asked Béla, who resided in
Veszprém with his barons then, responded that when he founded the provostry of Szeben, he had no intention of subordinating all Transylvanian Germans under the collegiate chapter, only those who were settled in the uninhabited wilderness given by his predecessor Géza II – that is, in the region of Altland (in the valley of the river
Olt or Alt). Sometime between 1191 and 1196, papal legate Gregorius clarified the content of the establishment and jurisdiction according to the interpretation described above. Despite the resolution, the conflict between the diocese and the collegiate chapter continued in the subsequent years. Upon the request of Adrian, the newly crowned
Pope Innocent III confirmed Gregorius' charter in 1198. In the next year, the pope permitted Adrian that if the archbishop of Esztergom, the provost of Szeben or the German clerics commit a violation of rights against him, or there is a suspicion of this, he can summon them to the
Apostolic See, since the right of collection of
tithe and parochial rights related to the Germans belongs to him in the area of the bishop's jurisdiction. Innocent's letter reveals that Job, Archbishop of Esztergom also tried to curtail the jurisdiction of the bishopric over German-inhabited areas. Simultaneously, Adrian also had a harsh and violent conflict with the
Kolozsmonostor Abbey, disputing the
Benedictines' privileges and exemptions. According to a bull of
Pope Honorius III from June 1222, Adrian once attacked the abbey with his soldiers, destroying its buildings, confiscating its privilege letters and capturing the abbot. His successor
William followed the same method against the Kolozsmonostor Abbey years later. Adrian is last mentioned as a living person in 1201. A non-authentic charter refers to him as the incumbent bishop in 1202. He died by 1204, when William succeeded him. ==Identification theory==