Hi @christian.dietz, @yanchick,
I reactivate this post because I think that I had the same error last Week.
I had Knime 3.6.1 installed and I could used Keras. Then I upgraded Knime to 3.7 (to try jupyter integration ;), and I obtained the same error message as in this post:
Finally I re-installed Knime 3.6.2 and then I could used Keras without problem.
All this without modifing my python/keras installation.
Thus for me it seems that the corrected error in Knime 3.6.1-2 came back …
Could you check this?
Thanks, Lionel