ValueError «You are trying to use the old GPU back-end» when importing keras

Question

I'm using Keras with the Theano backend on Ubuntu 16.04. My setup has been working without issues, however, all of a sudden I get the following error when I import Keras (import keras):

ValueError: You are trying to use the old GPU back-end. It was removed from Theano. Use device=cuda* now. See https://github.com/Theano/Theano/wiki/Converting-to-the-new-gpu-back-end%28gpuarray%29 for more information.

How do I resolve this?

Solution

You should change (or add) your environmental variable called THEANO_FLAGS. If you set the variable so that it contains device=cuda instead of device=gpu the error will be gone.

Also set the floating point precision to float32 when working on the GPU as that is usually much faster (THEANO_FLAGS='device=cuda,floatX=float32').

More info on this variable can be found here and here.

Comments

[Wilmar van Ommeren]

It is probably the environmental variable THEANO_FLAGS. If you set the variable so that it contains device=cuda instead of device=gpu it will be fixed.

[Tshilidzi Mudau]

hi @WilmarvanOmmeren, I just tried this now, and it worked. If you put your comment as an answer I will mark it as the correct answer. Thanks .

[cgl]

export THEANO_FLAGS=mode=FAST_RUN,device=cuda,floatX=float32

[anothernode]

Could you elaborate a bit on what this means exactly and how it answers the question?