# Hail Py4JError while calling z:is.hail.backend.spark.SparkBackend.apply **URL:** \ **Category:** Hail Query & hailctl\ **Created:** [September 29, 2021, 5:52am UTC](https://discuss.hail.is/t/hail-py4jerror-while-calling-z-is-hail-backend-spark-sparkbackend-apply/2272 "2021-09-29T05:52:44Z")\ **Posts on this page:** 3\ **Page:** 2
**Author:** ![johnc1231](https://yyz2.discourse-cdn.com/flex036/user_avatar/discuss.hail.is/johnc1231/32/286_2.png) [@johnc1231](https://discuss.hail.is/u/johnc1231)\ **Post date:** [September 30, 2021, 7:38pm UTC](https://discuss.hail.is/t/hail-py4jerror-while-calling-z-is-hail-backend-spark-sparkbackend-apply/2272/21 "2021-09-30T19:38:51Z")
^The above is because `async` is a keyword in Python 3.9. Try Python 3.8, it’s possible we don’t actually support 3.9 (I thought we did) ---
**Author:** ![johnc1231](https://yyz2.discourse-cdn.com/flex036/user_avatar/discuss.hail.is/johnc1231/32/286_2.png) [@johnc1231](https://discuss.hail.is/u/johnc1231)\ **Post date:** [September 30, 2021, 7:41pm UTC](https://discuss.hail.is/t/hail-py4jerror-while-calling-z-is-hail-backend-spark-sparkbackend-apply/2272/22 "2021-09-30T19:41:09Z")
Argh, nvm, that shouldn’t matter. That’s been true since Python 3.7. Anyway, the problem here is now also not hail related, somehow you’re calling some code in the `astor` library, which is not valid because it uses `async` as a function argument. `async` is a reserved word in Python that you can’t use as a function argument starting from Python 3.7. ---
**Author:** ![Niveditha](https://avatars.discourse-cdn.com/v4/letter/n/ba8739/32.png) [@Niveditha](https://discuss.hail.is/u/Niveditha)\ **Post date:** [October 1, 2021, 5:12am UTC](https://discuss.hail.is/t/hail-py4jerror-while-calling-z-is-hail-backend-spark-sparkbackend-apply/2272/23 "2021-10-01T05:12:07Z")
Thank you for all your suggestions! [Previous page](https://discuss.hail.is/t/hail-py4jerror-while-calling-z-is-hail-backend-spark-sparkbackend-apply/2272.md?page=1)