I'm guessing that the relatively new SigmoidGrad function is missing from the prepared AWS builds of the tensorflow 0.9.0 packages. Current tensorflow builds are 0.11.0
My model dies with u'SigmoidGrad': KeyError
I found the instructions on creating new AWS tensorflow binary builds, and will attempt do so for the region I need (us-east-1)
However, you might want to rebuild the images soon!