Ascii codec error "Error running query"

Hi there.
I am having trouble with ascii query characters. When I use no-ascii characters on query,it throws an exception. I have tried to add query = query.encode(‘utf-8’) to pg.py and oracle.py. (under def run_query(self,query,self)). But it is still throwing exception.
I use redash 7
my datasource is oracle.
I am on ubuntu 18.
I also looked to https://github.com/getredash/redash/issues?utf8=✓&q=is%3Aissue+is%3Aopen+utf-8. But no luck.