I have done several SOLR upgrades without any issues but Im getting the error below after upgrading the 1st of the 3 nodes in a cluster.
All nodes were running SOLR 6.6.0. I shutdown one of the replica nodes and did the upgrade to SOLR 7.7.3. The cluster has a SOLR 6 index.. When I start this node it comes up fine and joins the cluster but the replica on this node will not come on line. the upgraded node does not report any errors. The error below comes from the leader. Has anyone seen this before: 2020-12-11 14:31:30.733 WARN (qtp1800890735-57149) [c:Production s:shard1 r:core_node4 x:Production_shard1_replica4] o.a.s.u.p.DistributedUpdateProcessor Error sending update to http://solrnode:8983/solr <http://rdxrddm0040:8983/solr> org.apache.solr.client.solrj.impl.HttpSolrClient$RemoteSolrException: Error from server at http://solrnode:8983/solr/Production_shard1_replica3 <http://rdxrddm0040:8983/solr/ECFProduction_shard1_replica3>: Expected mime type application/octet-stream but got application/json. { "error":{ "metadata":[ "error-class","org.apache.solr.common.SolrException", "root-error-class","org.apache.solr.common.SolrException"], "msg":"SolrCore is loading", "code":503}} at org.apache.solr.client.solrj.impl.HttpSolrClient.executeMethod(HttpSolrClient.java:578) at org.apache.solr.client.solrj.impl.HttpSolrClient.request(HttpSolrClient.java:279) at org.apache.solr.client.solrj.impl.HttpSolrClient.request(HttpSolrClient.java:268) at org.apache.solr.client.solrj.impl.ConcurrentUpdateSolrClient.request(ConcurrentUpdateSolrClient.java:430) at org.apache.solr.client.solrj.SolrClient.request(SolrClient.java:1219) at org.apache.solr.update.SolrCmdDistributor.doRequest(SolrCmdDistributor.java:299) at org.apache.solr.update.SolrCmdDistributor.lambda$submit$0(SolrCmdDistributor.java:288) at java.util.concurrent.FutureTask.run(FutureTask.java:266) at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511) at java.util.concurrent.FutureTask.run(FutureTask.java:266) at com.codahale.metrics.InstrumentedExecutorService$InstrumentedRunnable.run(InstrumentedExecutorService.java:176) at org.apache.solr.common.util.ExecutorUtil$MDCAwareThreadPoolExecutor.lambda$execute$0(ExecutorUtil.java:229) at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617) at java.lang.Thread.run(Thread.java:748) -- *Paul Russell* *www.qflow.com <http://www.qflow.com>*
