I went to here to work through the R-keras example: https://tensorflow.rstudio.com/guide/keras/ There is a command 'predict_classes' that is now deprecated in keras. --> if I knew how to insert images, I would put the screenshot of the error here <-- You should keep your help documentation reasonably current. The way to get it to work is: model %>% predict(x_test) %>% k_argmax()