The US-led coalition has concluded what happened in Deir al-Zor on September 17th was a fatal case of mistaken identity.
They say they thought they were targeting so-called Islamic State fighters.
But they were wrong.
US Defence Department spokesman Peter Cook released the findings of an investigation into the incident by a four-member US-led team.
"The investigation determined that although the strikes likely hit forces aligned with the government of Syria, the strikes were conducted under a good faith belief that the strikes were targeting ISIL in accordance with the law of armed conflict. When we fall short of our high standards, as happened in this case, we learn from it and that's what we will do."
It's been confirmed two Australian aircraft dropped six of the bombs.
British and Danish aircraft also took part in the airstrikes, in which Russia claims more than 60 people were killed.
Australia's chief of Joint Operations, David Johnston, says it was a complex environment to operate in.
"These forces looked and acted like the Daesh fighters the coalition has been targeting for the last two years. They were not wearing recognisable military uniforms or displaying identifying flags or markings."
The US says it halted the strikes when Russia informed it of the error.
But the report suggests both sides committed crucial blunders.
It says Moscow repeatedly tried to contact the US-led coalition through a hotline to tell them that they were targeting the wrong group.
But when the designated point of contact was not available, rather than leave a message Russia waited 27 minutes in which time a further 15 air strikes took place.
The botched mission came less than a week into a fragile ceasefire.
Syrian President Bashar al-Assad has maintained he believes it was intentional.
Australia's Minister for Defence Personnel, Dan Tehan, says no Australian military personnel will be sanctioned.
"The most important thing we have to remember is that it's an incredibly complex operating environment that our military is involved in. We've looked at what are the lessons learned, were there mistakes made."
Australia's Defence Department says it will implement improved information-sharing between coalition partners.
