Recommender System : ValueError at / could not convert string to float:

I am trying to build a movie recommender web application using python and django. I am trying to use a command to take the movie's descriptions and create an information retrieval system to allow the user to find movies typing some relevant words. This tf-idf model is then saved in the Django cache together with the initial recommendation systems models (CF item-based and log-likelihood ratio). I am trying to build a movie recommender web ap