Solr 7.0 upgrade - Error opening new searcher

[#1]

I upgraded an existing Solr 6.6.0 instance to V7.0.0. On startup, only empty cores have come up cleanly. All cores that contain any data get an error "Error Opening New Searcher"

All these cores store their indexes on HDFS. This instance is a single node Solr cloud using external zookeeper. The HDFS platform is HDP 2.4.2

Just for starters, here is an example from solr.log for one such core:

2017-09-27 16:31:23.197 ERROR (coreContainerWorkExecutor-2-thread-1-processing-n:SolrServer:9031_solr) [   ] o.a.s.c.CoreContainer Error waiting for SolrCore to be created
java.util.concurrent.ExecutionException: org.apache.solr.common.SolrException: Unable to create core [CoreName_shard1_replica1]
        at java.util.concurrent.FutureTask.report(FutureTask.java:122)
        at java.util.concurrent.FutureTask.get(FutureTask.java:192)
        at org.apache.solr.core.CoreContainer.lambda$load$118(CoreContainer.java:647)
        at org.apache.solr.core.CoreContainer$Lambda$132/1829217853.run(Unknown Source)
        at com.codahale.metrics.InstrumentedExecutorService$InstrumentedRunnable.run(InstrumentedExecutorService.java:176)
        at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
        at java.util.concurrent.FutureTask.run(FutureTask.java:266)
        at org.apache.solr.common.util.ExecutorUtil$MDCAwareThreadPoolExecutor.lambda$execute$128(ExecutorUtil.java:188)
        at org.apache.solr.common.util.ExecutorUtil$MDCAwareThreadPoolExecutor$Lambda$15/991515462.run(Unknown Source)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
        at java.lang.Thread.run(Thread.java:745)
Caused by: org.apache.solr.common.SolrException: Unable to create core [CoreName_shard1_replica1]
        at org.apache.solr.core.CoreContainer.createFromDescriptor(CoreContainer.java:996)
        at org.apache.solr.core.CoreContainer.lambda$load$117(CoreContainer.java:619)
        at org.apache.solr.core.CoreContainer$Lambda$131/1622458036.call(Unknown Source)
        at com.codahale.metrics.InstrumentedExecutorService$InstrumentedCallable.call(InstrumentedExecutorService.java:197)
        ... 6 more
Caused by: org.apache.solr.common.SolrException: Error opening new searcher
        at org.apache.solr.core.SolrCore.<init>(SolrCore.java:988)
        at org.apache.solr.core.SolrCore.<init>(SolrCore.java:843)
        at org.apache.solr.core.CoreContainer.createFromDescriptor(CoreContainer.java:980)
        ... 9 more
Caused by: org.apache.solr.common.SolrException: Error opening new searcher
        at org.apache.solr.core.SolrCore.openNewSearcher(SolrCore.java:2066)
        at org.apache.solr.core.SolrCore.getSearcher(SolrCore.java:2186)
        at org.apache.solr.core.SolrCore.initSearcher(SolrCore.java:1071)
        at org.apache.solr.core.SolrCore.<init>(SolrCore.java:960)
        ... 11 more
Caused by: java.lang.NullPointerException
        at java.util.Objects.requireNonNull(Objects.java:203)
        at java.util.Optional.<init>(Optional.java:96)
        at java.util.Optional.of(Optional.java:108)
        at java.util.stream.ReduceOps$2ReducingSink.get(ReduceOps.java:129)
        at java.util.stream.ReduceOps$2ReducingSink.get(ReduceOps.java:107)
        at java.util.stream.ReduceOps$ReduceOp.evaluateSequential(ReduceOps.java:708)
        at java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:234)
        at java.util.stream.ReferencePipeline.reduce(ReferencePipeline.java:479)
        at org.apache.solr.index.SlowCompositeReaderWrapper.<init>(SlowCompositeReaderWrapper.java:76)
        at org.apache.solr.index.SlowCompositeReaderWrapper.wrap(SlowCompositeReaderWrapper.java:57)
        at org.apache.solr.search.SolrIndexSearcher.<init>(SolrIndexSearcher.java:252)
        at org.apache.solr.core.SolrCore.openNewSearcher(SolrCore.java:2034)
        ... 14 more

Any ideas?

[#2]

Thanks @Cassandra Targett. I've reverted to 6.6.0 and will await V7.0.1

Regards

Tony

[#3]

@tonybolt, Solr 7.0.1 was just released this afternoon.