Hi All, We have encountered an issue while upgrading our solr cloud from v8.10 to v9.6.1. We use a collection with 56 shards [each having a single replica], hosted across a cluster of 8 nodes. Solr queries contain _route_ parameter to decide which shards/ replicas will be used for the respective query.
*Problem Description:* In solr8 if we stop/ restart a node for a maintenance activity, we did not encounter any 5xx, but on solr9 we are facing multiple 5xx. On further debugging, we noticed that all the queries which are being routed to *different shards of a single node* [which is stopped], are returning 5xx which was not the case in solr 8. On replicating this on solr8, the queries are simply returning with partialResults=true flag and 0 results. Important to note that if a solr 9 query is being routed to multiple shards out of which shard is present on some other node, it will be returned with partialResults=true and status=0, and 5xx is returned only if query is routed to shards of a single node [which is stopped]. *1. Is someone aware of any changes done in solr9, to handle such cases?* *2. Is there a way to avoid 5xx in these cases on solr9 as well?*
