The code assumes that .html files in Russian and English will mixed in the directory provided as argument just like the samples. When a directory with files just in English but not Russian or vice-versa the code breaks because it is waiting for both types to be present. Could you provide directory with both type of files(English and Russian)? The http server for what I saw in the log probably failing because redis-server is not installed and cant make a proper connection. The issue with json decoding is because of a warning appearing. Could you provide any support for these?