# Liftover NullPointerException **URL:** \ **Category:** Hail Query & hailctl\ **Created:** [April 26, 2019, 9:50am UTC](https://discuss.hail.is/t/liftover-nullpointerexception/944 "2019-04-26T09:50:29Z")\ **Posts on this page:** 7\ **Page:** 1
**Author:** ![Aditya](https://avatars.discourse-cdn.com/v4/letter/a/df705f/32.png) [@Aditya](https://discuss.hail.is/u/Aditya)\ **Post date:** [April 26, 2019, 9:50am UTC](https://discuss.hail.is/t/liftover-nullpointerexception/944/1 "2019-04-26T09:50:29Z")
Hi Team, Sorry if I am using a wrong thread to post an issue with lift over. Let me know if I shall raise a new entry for it but would need your advise for below scenario: I was trying to use hail lift over on a specific dataset for GRCH38 to GRCH37 conversion. I am getting some null pointer exceptions. Below is the code I am using: rg37 = hl.get\_reference(‘GRCh37’) rg38 = hl.get\_reference(‘GRCh38’) rg38.add\_liftover('gs://hail-common/references/grch38\_to\_grch37.over.chain.gz, rg37) ht = ht.annotate(new\_pos=hl.liftover(hl.locus(ht.chr,ht.pos, ‘GRCh38’), ‘GRCh37’)) Error Details: TaskSetManager: WARN: Lost task 4.0 in stage 0.0 (TID 22, , executor 8): java.lang.NullPointerException at is.hail.codegen.generated.C0.method1(Unknown Source) at is.hail.codegen.generated.C0.apply(Unknown Source) at is.hail.codegen.generated.C0.apply(Unknown Source) at is.hail.expr.TableMapRows$$anonfun$65$$anonfun$apply$32.apply(Relational.scala:2080) at is.hail.expr.TableMapRows$$anonfun$65$$anonfun$apply$32.apply(Relational.scala:2079) at scala.collection.Iterator$$anon$11.next(Iterator.scala:409) at scala.collection.Iterator$$anon$12.next(Iterator.scala:444) at scala.collection.Iterator$$anon$11.next(Iterator.scala:409) at scala.collection.Iterator$$anon$12.next(Iterator.scala:444) at scala.collection.Iterator$$anon$11.next(Iterator.scala:409) at scala.collection.Iterator$$anon$12.next(Iterator.scala:444) at scala.collection.Iterator$$anon$11.next(Iterator.scala:409) at scala.collection.Iterator$$anon$12.next(Iterator.scala:444) at scala.collection.Iterator$$anon$11.next(Iterator.scala:409) at scala.collection.Iterator$$anon$11.next(Iterator.scala:409) at scala.collection.Iterator$$anon$11.next(Iterator.scala:409) at org.apache.spark.api.python.SerDeUtil$AutoBatchedPickler.next(SerDeUtil.scala:121) at org.apache.spark.api.python.SerDeUtil$AutoBatchedPickler.next(SerDeUtil.scala:112) at scala.collection.Iterator$class.foreach(Iterator.scala:893) at org.apache.spark.api.python.SerDeUtil$AutoBatchedPickler.foreach(SerDeUtil.scala:112) at org.apache.spark.api.python.PythonRDD$.writeIteratorToStream(PythonRDD.scala:509) at org.apache.spark.api.python.PythonRunner$WriterThread$$anonfun$run$3.apply(PythonRDD.scala:333) at org.apache.spark.util.Utils$.logUncaughtExceptions(Utils.scala:1954) at org.apache.spark.api.python.PythonRunner$WriterThread.run(PythonRDD.scala:269) I tried this on a different dataset and it works so wondering if it could be a data issue. Is there a way to get some more logging on it? Thanks in advance, Aditya Pandit ---
**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:** [April 26, 2019, 12:58pm UTC](https://discuss.hail.is/t/liftover-nullpointerexception/944/2 "2019-04-26T12:58:31Z")
Moved to a new thread. This is definitely a Hail bug, but probably data-dependent, which could help us figure out what it is. What version of hail are you running? ---
**Author:** ![Aditya](https://avatars.discourse-cdn.com/v4/letter/a/df705f/32.png) [@Aditya](https://discuss.hail.is/u/Aditya)\ **Post date:** [April 26, 2019, 2:09pm UTC](https://discuss.hail.is/t/liftover-nullpointerexception/944/3 "2019-04-26T14:09:57Z")
We are using hail 0.2 ---
**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:** [April 26, 2019, 2:11pm UTC](https://discuss.hail.is/t/liftover-nullpointerexception/944/4 "2019-04-26T14:11:06Z")
sorry, full version with git SHA. should be in the error message ---
**Author:** ![Aditya](https://avatars.discourse-cdn.com/v4/letter/a/df705f/32.png) [@Aditya](https://discuss.hail.is/u/Aditya)\ **Post date:** [April 26, 2019, 2:12pm UTC](https://discuss.hail.is/t/liftover-nullpointerexception/944/5 "2019-04-26T14:12:33Z")
Sorry about that. It’s Hail version devel-6942d090d618 ---
**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:** [April 26, 2019, 2:17pm UTC](https://discuss.hail.is/t/liftover-nullpointerexception/944/6 "2019-04-26T14:17:12Z")
that’s an extremely old version – from before 0.2 was promoted out of beta in October! Please update to the latest Hail version – I’d be very surprised if the problem persists. ---
**Author:** ![Aditya](https://avatars.discourse-cdn.com/v4/letter/a/df705f/32.png) [@Aditya](https://discuss.hail.is/u/Aditya)\ **Post date:** [April 26, 2019, 2:23pm UTC](https://discuss.hail.is/t/liftover-nullpointerexception/944/7 "2019-04-26T14:23:08Z")
Thanks for the advise. Will check for a version upgrade.