[Answered ]-Failed to add documents to Solr: [Reason: None]

You need to update schema.xml of your solr engine, as it written here:

“You’ll need to revise your schema. You can generate this from your application (once Haystack is installed and setup) by running ./manage.py build_solr_schema. Take the output from that command and place it in apache-solr-3.5.0/example/solr/conf/schema.xml. Then restart Solr.”