# GCP Py4JNetworkError("Answer from Java side is empty")

**URL:** <https://discuss.hail.is/t/gcp-py4jnetworkerror-answer-from-java-side-is-empty/630>\
**Category:** Hail Query & hailctl\
**Created:** [August 30, 2018, 5:25pm UTC](https://discuss.hail.is/t/gcp-py4jnetworkerror-answer-from-java-side-is-empty/630 "2018-08-30T17:25:27Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![greg-botwin](https://yyz2.discourse-cdn.com/flex036/user_avatar/discuss.hail.is/greg-botwin/32/135_2.png) [@greg-botwin](https://discuss.hail.is/u/greg-botwin)\
**Post date:** [August 30, 2018, 5:25pm UTC](https://discuss.hail.is/t/gcp-py4jnetworkerror-answer-from-java-side-is-empty/630/1 "2018-08-30T17:25:27Z")

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Hi,

I am running hail on GCP after starting my cluster using the cloudtools helpers. I am running Hail version devel-5702f5c6b299.

Yesterday my code seemed to be working fine, but today, I am getting the following error. `rsid` is listed as a row field in the mt.

Was anything changed?

```
hl.init()
mt = hl.read_matrix_table('gs://hail-datasets/hail-data/1000_genomes_phase3_autosomes.GRCh37.mt')
mt.describe() ...
mt.rsid.show(5)
ERROR:root:Exception while sending command.
Traceback (most recent call last):
  File "/usr/lib/spark/python/lib/py4j-0.10.4-src.zip/py4j/java_gateway.py", line 1035, in send_command
    raise Py4JNetworkError("Answer from Java side is empty")
py4j.protocol.Py4JNetworkError: Answer from Java side is empty

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/usr/lib/spark/python/lib/py4j-0.10.4-src.zip/py4j/java_gateway.py", line 883, in send_command
    response = connection.send_command(command)
  File "/usr/lib/spark/python/lib/py4j-0.10.4-src.zip/py4j/java_gateway.py", line 1040, in send_command
    "Error while receiving", e, proto.ERROR_ON_RECEIVE)
py4j.protocol.Py4JNetworkError: Error while receiving

```

Thanks for your support.

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**Author:** ![tpoterba](https://yyz2.discourse-cdn.com/flex036/user_avatar/discuss.hail.is/tpoterba/32/61_2.png) [@tpoterba](https://discuss.hail.is/u/tpoterba)\
**Post date:** [August 30, 2018, 6:41pm UTC](https://discuss.hail.is/t/gcp-py4jnetworkerror-answer-from-java-side-is-empty/630/2 "2018-08-30T18:41:47Z")

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Can you update to latest hash? I think this commit broke as we fiddled with our deployment server.

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**Author:** ![danking](https://yyz2.discourse-cdn.com/flex036/user_avatar/discuss.hail.is/danking/32/43_2.png) [@danking](https://discuss.hail.is/u/danking)\
**Post date:** [August 30, 2018, 6:46pm UTC](https://discuss.hail.is/t/gcp-py4jnetworkerror-answer-from-java-side-is-empty/630/3 "2018-08-30T18:46:57Z")

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Hey @greg-botwin , I’m sorry this happened to you. If you restart your cluster you should retrieve a SHA that works correctly. We had an issue with a bad SHA getting past our testing system and you happened to start a cluster while that SHA was still available. Those JARs have now been deleted and the latest SHA reset to a working version.

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**Author:** ![greg-botwin](https://yyz2.discourse-cdn.com/flex036/user_avatar/discuss.hail.is/greg-botwin/32/135_2.png) [@greg-botwin](https://discuss.hail.is/u/greg-botwin)\
**Post date:** [August 30, 2018, 7:13pm UTC](https://discuss.hail.is/t/gcp-py4jnetworkerror-answer-from-java-side-is-empty/630/4 "2018-08-30T19:13:47Z")

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Thanks @tpoterba @danking created a new cluster with version devel-b544caa82246 (its awesome how easy it is with cloudtools) and everything is working perfectly now!

Thanks,  
Greg

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**Author:** ![tpoterba](https://yyz2.discourse-cdn.com/flex036/user_avatar/discuss.hail.is/tpoterba/32/61_2.png) [@tpoterba](https://discuss.hail.is/u/tpoterba)\
**Post date:** [August 30, 2018, 7:26pm UTC](https://discuss.hail.is/t/gcp-py4jnetworkerror-answer-from-java-side-is-empty/630/5 "2018-08-30T19:26:02Z")

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Great!