While working on a project today, i encountered a serious ballache in the form of this:

mx.rpc.Fault (@14f27331)
[inherited]
faultCode “Server.Acknowledge.Failed”
faultDetail “Was expecting message ’93EDDF20-516F-2C3F-AA63-619BAB9DA793′ but received ”.”
faultString “Didn’t receive an acknowledgement of message”
rootCause null

AMFPHP, for all it’s wonder and usefulness, doesn’t document its errors very well. Very irritating. After much digging, i found that the solution to this isn’t actually anything to do with the AMFPHP framework, nor with Flex! It’s stupid little error in PHP… Make sure that you aren’t trying to return an array or object in PHP that has an undefined index or property. I slapped my forehead when i realised the error of my ways.

Sigh.