[Answered ]-Django-tables2: "Invalid block tag: 'query string' "

From what I see, you are loading only render_table from django_tables2! If you wanted to also use the querystring tag you could instead do a {% load django_tables2 %} to load all tags!

As a more general comment, I see that you want to add filtering to the tables. I am not sure why you need that — please check my answer to this question Django Tables – Column Filtering for an extensive analysis of filtering on django-tables2.