pylti1p3.exception.LtiException: Invalid Nonce

[misilot]

Hello,

We are seeing the error pylti1p3.exception.LtiException: Invalid Nonce happen a lot. The user can typical go back, refresh the page, and it works. Though if they refresh again, it takes another refresh to have the page load.

We are using Canvas if that helps?

readinglistlti-test-reading-1  | [2023-10-20 13:39:30,427] ERROR in app: Exception on /launch/ [POST]
readinglistlti-test-reading-1  | Traceback (most recent call last):
readinglistlti-test-reading-1  |   File "/venv/readinglistlti-MATOk_fk-py3.11/lib/python3.11/site-packages/flask/app.py", line 2190, in wsgi_app
readinglistlti-test-reading-1  |     response = self.full_dispatch_request()
readinglistlti-test-reading-1  |                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
readinglistlti-test-reading-1  |   File "/venv/readinglistlti-MATOk_fk-py3.11/lib/python3.11/site-packages/flask/app.py", line 1486, in full_dispatch_request
readinglistlti-test-reading-1  |     rv = self.handle_user_exception(e)
readinglistlti-test-reading-1  |          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
readinglistlti-test-reading-1  |   File "/venv/readinglistlti-MATOk_fk-py3.11/lib/python3.11/site-packages/flask/app.py", line 1484, in full_dispatch_request
readinglistlti-test-reading-1  |     rv = self.dispatch_request()
readinglistlti-test-reading-1  |          ^^^^^^^^^^^^^^^^^^^^^^^
readinglistlti-test-reading-1  |   File "/venv/readinglistlti-MATOk_fk-py3.11/lib/python3.11/site-packages/flask/app.py", line 1469, in dispatch_request
readinglistlti-test-reading-1  |     return self.ensure_sync(self.view_functions[rule.endpoint])(**view_args)
readinglistlti-test-reading-1  |            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
readinglistlti-test-reading-1  |   File "/code/reading/app.py", line 112, in launch
readinglistlti-test-reading-1  |     message_launch_data = message_launch.get_launch_data()
readinglistlti-test-reading-1  |                           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
readinglistlti-test-reading-1  |   File "/venv/readinglistlti-MATOk_fk-py3.11/lib/python3.11/site-packages/pylti1p3/message_launch.py", line 529, in get_launch_data
readinglistlti-test-reading-1  |     return self._get_jwt_body()
readinglistlti-test-reading-1  |            ^^^^^^^^^^^^^^^^^^^^
readinglistlti-test-reading-1  |   File "/venv/readinglistlti-MATOk_fk-py3.11/lib/python3.11/site-packages/pylti1p3/message_launch.py", line 330, in _get_jwt_body
readinglistlti-test-reading-1  |     self.validate()
readinglistlti-test-reading-1  |   File "/venv/readinglistlti-MATOk_fk-py3.11/lib/python3.11/site-packages/pylti1p3/message_launch.py", line 317, in validate
readinglistlti-test-reading-1  |     .validate_nonce()
readinglistlti-test-reading-1  |      ^^^^^^^^^^^^^^^^
readinglistlti-test-reading-1  |   File "/code/reading/app.py", line 63, in validate_nonce
readinglistlti-test-reading-1  |     return super().validate_nonce()
readinglistlti-test-reading-1  |            ^^^^^^^^^^^^^^^^^^^^^^^^
readinglistlti-test-reading-1  |   File "/venv/readinglistlti-MATOk_fk-py3.11/lib/python3.11/site-packages/pylti1p3/message_launch.py", line 670, in validate_nonce
readinglistlti-test-reading-1  |     raise LtiException("Invalid Nonce")
readinglistlti-test-reading-1  | pylti1p3.exception.LtiException: Invalid Nonce

Thanks for your help!

[jsogg]

I was getting a lot of nonce validation errors until I changed gunicorn from 4 workers to 1 worker. Possibly related to data storage and it being tied to the particular worker, possibly?