The Saudi-led coalition bombing Houthi rebels in Yemen has said it attacked a funeral hall in the capital, Sanaa, based on "bad information".
At least 140 people were killed, most of them civilians, in the attack on 8 October - one of the single worst death tolls in the two-year conflict.
An inquiry blames "non-compliance with coalition rules of engagement" and "the issuing of incorrect information".
The attack was heavily criticised internationally.
The 14-nation Saudi-led inquiry, carried out by the Joint Incidents Assessment Team, said coalition aircraft were wrongly told that the funeral hall was full of Houthi leaders.
It said "a party affiliated to the Yemeni presidency of the general chief of staff" was to blame.
The inquiry also apportioned blame to the Air Operation Center in Yemen for directing aircraft onto the target without obtaining approval from the coalition's command.
The investigation called for families of the victims to be compensated. An estimated 600 people were injured in the bombing.
"Coalition forces must immediately review their rules of engagement and update their procedures to ensure adherence in future," the inquiry team said.