His sudden announcement really fluttered the dovecote.
flutter the dovecote
idiomTo create a disturbance, usually within a group of people who are generally placid and unexcited.
Origin
first recorded 17th c. disputed originPossibly from Coriolanus (written c. 1608–1609; published 1623) by the English playwright William Shakespeare (1564–1616), Act V, scene vi (spelling modernized): “[L]ike an eagle in a dovecote, I / Fluttered your Volcians in Corioles.”
The arrival of the unexpected audit notice fluttered the dovecote among the quiet accounting staff.
The radical proposal from the new director fluttered the dovecote, causing a stir among the long-serving members who preferred the status quo.