# Null\_pointer\_exception: Cannot invoke "String.equals(Object)" because the return value of "org.apache.lucene.search.SortField.getField()" is null **URL:** \ **Category:** Elasticsearch\ **Created:** [March 8, 2023, 1:33am UTC](https://discuss.elastic.co/t/null-pointer-exception-cannot-invoke-string-equals-object-because-the-return-value-of-org-apache-lucene-search-sortfield-getfield-is-null/327235 "2023-03-08T01:33:23Z")\ **Posts on this page:** 3\ **Page:** 1
**Author:** ![davidgAID](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/davidgaid/32/110566_2.png) [@davidgAID](https://discuss.elastic.co/u/davidgAID)\ **Post date:** [March 8, 2023, 1:33am UTC](https://discuss.elastic.co/t/null-pointer-exception-cannot-invoke-string-equals-object-because-the-return-value-of-org-apache-lucene-search-sortfield-getfield-is-null/327235/1 "2023-03-08T01:33:23Z")
This is on Elasticsearch 8.6.2. I have a pretty mundane query that I want to paginate via `search_after`. The initial query looks like this: ```auto { "_source": true, "collapse": { "field": "collapse_col" }, "query": { "bool": { "filter": [ {"term": {"array_col.attr_1": 12345}} ] } }, "size": 10000, "sort": ["_doc"] } ``` The first, or the first few, requests in the pagination will return OK. But at some point, the query fails: ```auto { "_source": true, "collapse": { "field": "collapse_col" }, "query": { "bool": { "filter": [ {"term": {"array_col.attr_1": 12345}} ] } }, "search_after": [1311485], "size": 10000, "sort": ["_doc"] } ``` The result looks like: ```auto { "error" : { "root_cause" : [ { "type" : "null_pointer_exception", "reason" : "Cannot invoke \"String.equals(Object)\" because the return value of \"org.apache.lucene.search.SortField.getField()\" is null" } ], "type" : "search_phase_execution_exception", "reason" : "all shards failed", "phase" : "query", "grouped" : true, "failed_shards" : [ { "shard" : 0, "index" : "indexname_2023-03-07-14-12-54", "node" : "node_id", "reason" : { "type" : "null_pointer_exception", "reason" : "Cannot invoke \"String.equals(Object)\" because the return value of \"org.apache.lucene.search.SortField.getField()\" is null" } } ], "caused_by" : { "type" : "null_pointer_exception", "reason" : "Cannot invoke \"String.equals(Object)\" because the return value of \"org.apache.lucene.search.SortField.getField()\" is null", "caused_by" : { "type" : "null_pointer_exception", "reason" : "Cannot invoke \"String.equals(Object)\" because the return value of \"org.apache.lucene.search.SortField.getField()\" is null" } } }, "status" : 500 } ``` From one of the coordinating nodes, we had a log like this: ```auto [2023-03-07T20:10:12,643][WARN][r.suppressed] [node-name] path: /index_name/_search, params: {index=index_name} org.elasticsearch.action.search.SearchPhaseExecutionException: all shards failed at org.elasticsearch.action.search.AbstractSearchAsyncAction.onPhaseFailure(AbstractSearchAsyncAction.java:728) ~[elasticsearch-8.6.2.jar:?] at org.elasticsearch.action.search.AbstractSearchAsyncAction.executeNextPhase(AbstractSearchAsyncAction.java:418) ~[elasticsearch-8.6.2.jar:?] at org.elasticsearch.action.search.AbstractSearchAsyncAction.onPhaseDone(AbstractSearchAsyncAction.java:760) ~[elasticsearch-8.6.2.jar:?] at org.elasticsearch.action.search.AbstractSearchAsyncAction.onShardFailure(AbstractSearchAsyncAction.java:512) ~[elasticsearch-8.6.2.jar:?] at org.elasticsearch.action.search.AbstractSearchAsyncAction$1.onFailure(AbstractSearchAsyncAction.java:349) ~[elasticsearch-8.6.2.jar:?] at org.elasticsearch.action.ActionListener$Delegating.onFailure(ActionListener.java:92) ~[elasticsearch-8.6.2.jar:?] at org.elasticsearch.action.ActionListenerResponseHandler.handleException(ActionListenerResponseHandler.java:48) ~[elasticsearch-8.6.2.jar:?] at org.elasticsearch.action.search.SearchTransportService$ConnectionCountingHandler.handleException(SearchTransportService.java:642) ~[elasticsearch-8.6.2.jar:?] at org.elasticsearch.transport.TransportService$UnregisterChildTransportResponseHandler.handleException(TransportService.java:1646) ~[elasticsearch-8.6.2.jar:?] at org.elasticsearch.transport.TransportService$ContextRestoreResponseHandler.handleException(TransportService.java:1372) ~[elasticsearch-8.6.2.jar:?] at org.elasticsearch.transport.InboundHandler.doHandleException(InboundHandler.java:410) ~[elasticsearch-8.6.2.jar:?] at org.elasticsearch.transport.InboundHandler.handleException(InboundHandler.java:397) ~[elasticsearch-8.6.2.jar:?] at org.elasticsearch.transport.InboundHandler.handlerResponseError(InboundHandler.java:388) ~[elasticsearch-8.6.2.jar:?] at org.elasticsearch.transport.InboundHandler.messageReceived(InboundHandler.java:141) ~[elasticsearch-8.6.2.jar:?] at org.elasticsearch.transport.InboundHandler.inboundMessage(InboundHandler.java:95) ~[elasticsearch-8.6.2.jar:?] at org.elasticsearch.transport.TcpTransport.inboundMessage(TcpTransport.java:808) ~[elasticsearch-8.6.2.jar:?] at org.elasticsearch.transport.InboundPipeline.forwardFragments(InboundPipeline.java:149) ~[elasticsearch-8.6.2.jar:?] at org.elasticsearch.transport.InboundPipeline.doHandleBytes(InboundPipeline.java:121) ~[elasticsearch-8.6.2.jar:?] at org.elasticsearch.transport.InboundPipeline.handleBytes(InboundPipeline.java:86) ~[elasticsearch-8.6.2.jar:?] at org.elasticsearch.transport.netty4.Netty4MessageInboundHandler.channelRead(Netty4MessageInboundHandler.java:63) ~[?:?] at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:444) ~[?:?] at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:420) ~[?:?] at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:412) ~[?:?] at io.netty.handler.logging.LoggingHandler.channelRead(LoggingHandler.java:280) ~[?:?] at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:442) ~[?:?] at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:420) ~[?:?] at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:412) ~[?:?] at io.netty.handler.codec.MessageToMessageDecoder.channelRead(MessageToMessageDecoder.java:103) ~[?:?] at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:444) ~[?:?] at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:420) ~[?:?] at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:412) ~[?:?] at io.netty.channel.DefaultChannelPipeline$HeadContext.channelRead(DefaultChannelPipeline.java:1410) ~[?:?] at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:440) ~[?:?] at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:420) ~[?:?] at io.netty.channel.DefaultChannelPipeline.fireChannelRead(DefaultChannelPipeline.java:919) ~[?:?] at io.netty.channel.nio.AbstractNioByteChannel$NioByteUnsafe.read(AbstractNioByteChannel.java:166) ~[?:?] at io.netty.channel.nio.NioEventLoop.processSelectedKey(NioEventLoop.java:788) ~[?:?] at io.netty.channel.nio.NioEventLoop.processSelectedKeysPlain(NioEventLoop.java:689) ~[?:?] at io.netty.channel.nio.NioEventLoop.processSelectedKeys(NioEventLoop.java:652) ~[?:?] at io.netty.channel.nio.NioEventLoop.run(NioEventLoop.java:562) ~[?:?] at io.netty.util.concurrent.SingleThreadEventExecutor$4.run(SingleThreadEventExecutor.java:997) ~[?:?] at io.netty.util.internal.ThreadExecutorMap$2.run(ThreadExecutorMap.java:74) ~[?:?] at java.lang.Thread.run(Thread.java:1589) ~[?:?] Caused by: org.elasticsearch.ElasticsearchException$1: Cannot invoke "String.equals(Object)" because the return value of "org.apache.lucene.search.SortField.getField()" is null at org.elasticsearch.ElasticsearchException.guessRootCauses(ElasticsearchException.java:640) ~[elasticsearch-8.6.2.jar:?] at org.elasticsearch.action.search.AbstractSearchAsyncAction.executeNextPhase(AbstractSearchAsyncAction.java:416) ~[elasticsearch-8.6.2.jar:?] ... 41 more Caused by: java.lang.NullPointerException: Cannot invoke "String.equals(Object)" because the return value of "org.apache.lucene.search.SortField.getField()" is null at org.elasticsearch.search.searchafter.SearchAfterBuilder.buildFieldDoc(SearchAfterBuilder.java:104) ~[elasticsearch-8.6.2.jar:?] at org.elasticsearch.search.SearchService.parseSource(SearchService.java:1335) ~[elasticsearch-8.6.2.jar:?] at org.elasticsearch.search.SearchService.createContext(SearchService.java:986) ~[elasticsearch-8.6.2.jar:?] at org.elasticsearch.search.SearchService.executeQueryPhase(SearchService.java:630) ~[elasticsearch-8.6.2.jar:?] at org.elasticsearch.search.SearchService.lambda$executeQueryPhase$2(SearchService.java:495) ~[elasticsearch-8.6.2.jar:?] at org.elasticsearch.action.ActionRunnable$2.accept(ActionRunnable.java:50) ~[elasticsearch-8.6.2.jar:?] at org.elasticsearch.action.ActionRunnable$2.accept(ActionRunnable.java:47) ~[elasticsearch-8.6.2.jar:?] at org.elasticsearch.action.ActionRunnable$3.doRun(ActionRunnable.java:72) ~[elasticsearch-8.6.2.jar:?] at org.elasticsearch.common.util.concurrent.AbstractRunnable.run(AbstractRunnable.java:26) ~[elasticsearch-8.6.2.jar:?] at org.elasticsearch.common.util.concurrent.TimedRunnable.doRun(TimedRunnable.java:33) ~[elasticsearch-8.6.2.jar:?] at org.elasticsearch.common.util.concurrent.ThreadContext$ContextPreservingAbstractRunnable.doRun(ThreadContext.java:917) ~[elasticsearch-8.6.2.jar:?] at org.elasticsearch.common.util.concurrent.AbstractRunnable.run(AbstractRunnable.java:26) ~[elasticsearch-8.6.2.jar:?] at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1144) ~[?:?] at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:642) ~[?:?] at java.lang.Thread.run(Thread.java:1589) ~[?:?] ``` ---
**Author:** ![davidgAID](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/davidgaid/32/110566_2.png) [@davidgAID](https://discuss.elastic.co/u/davidgAID)\ **Post date:** [March 8, 2023, 4:35pm UTC](https://discuss.elastic.co/t/null-pointer-exception-cannot-invoke-string-equals-object-because-the-return-value-of-org-apache-lucene-search-sortfield-getfield-is-null/327235/2 "2023-03-08T16:35:29Z")
I think this is related to using a `collapse` on one column and `search_after` / `sort` on a different, second column, and especially if that second one was `_doc`. If I sort/search\_after on the `collapse_col`, things work fine. If I try to do a sort on `["collapse_col", "_doc"]` I get `Cannot use [collapse] in conjunction with [search_after] unless the search is sorted on the same field. Multiple sort fields are not allowed.`, which is expected. So maybe this is some bug where it is not getting caught that the collapse and sort fields are not the same and it doesn't detect this when the sort field is `_doc`? This doesn't appear to be any sort of data corruption as I can trigger the null pointer by shrinking the size down to 1 and doing a `search_after` to fetch the second document. Adding the `search_after` causes the null pointer exception, the initial search with no `search_after` works fine. ---
**Author:** ![system](https://us1.discourse-cdn.com/elastic/original/3X/1/a/1ac57faf039f6b580b3f104ef42a2a89e41014de.png) [@system](https://discuss.elastic.co/u/system)\ **Post date:** [April 5, 2023, 4:35pm UTC](https://discuss.elastic.co/t/null-pointer-exception-cannot-invoke-string-equals-object-because-the-return-value-of-org-apache-lucene-search-sortfield-getfield-is-null/327235/3 "2023-04-05T16:35:32Z")
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