Tornado HTTPS Package Error - python-3.x

Question

I have a simple example of a Python (3.6) Tornado (4.5.2) server and I am attempting to add ssl certs for testing. I have determined it is finding the key and csr files. Here is what my code looks like with a stack trace following detailing the error. Has anyone run into this or solved it?
import tornado.httpserver
import tornado.ioloop
import tornado.web
class indexHandler(tornado.web.RequestHandler):
def get(self):
self.write("hello")
application = tornado.web.Application([
(r'/', indexHandler),
])
if __name__ == '__main__':
http_server = tornado.httpserver.HTTPServer(application, ssl_options={
"certfile": "cert/ig.csr",
"keyfile": "cert/ig.key",
})
http_server.listen(443)
tornado.ioloop.IOLoop.instance().start()
Running on Python 3.6.4 and the server runs but when the page is accessed as https://localhost, it throws the following exception. What am I missing?
ERROR:asyncio:Exception in callback BaseAsyncIOLoop._handle_events(5, 1)
handle: <Handle BaseAsyncIOLoop._handle_events(5, 1)>
Traceback (most recent call last):
File "/<python path>/asyncio/events.py", line 145, in _run
self._callback(*self._args)
File "/<python path>/site-packages/tornado/platform/asyncio.py", line 102, in _handle_events
handler_func(fileobj, events)
File "/<python path>/site-packages/tornado/stack_context.py", line 276, in null_wrapper
return fn(*args, **kwargs)
File "/<python path>/site-packages/tornado/netutil.py", line 252, in accept_handler
callback(connection, address)
File "/<python path>/site-packages/tornado/tcpserver.py", line 264, in _handle_connection
do_handshake_on_connect=False)
File "/<python path>/site-packages/tornado/netutil.py", line 551, in ssl_wrap_socket
context = ssl_options_to_context(ssl_options)
File "/<python path>/site-packages/tornado/netutil.py", line 526, in ssl_options_to_context
context.load_cert_chain(ssl_options['certfile'], ssl_options.get('keyfile', None))
ssl.SSLError: [SSL] PEM lib (_ssl.c:3337)
In above error message, /<python path>/ is equal to:
"/usr/local/Cellar/python3/3.6.4_2/Frameworks/Python.framework/Versions/3.6/lib/python3.6/"

Answer 1

Its because the signature of the you certificate and the key doesn't match.

Answer 2

OK - I found it!! There are several online resources for determining if your certificate file and key match. I used THIS and they did not match. A quick call to Comodo (cert was thru Namecheap and then thru them) and they fixed it.
Lesson: Validate the key and certificate first!