Solr: Error while creating remote solr core.

[Former Member]

Hello

After upgrading solr from 4.7 to 5.3 I get the following errors when queries are executed during restart of one of the nodes (2 solr nodes, master/slave):

hybris-log

 de.hybris.platform.solrfacetsearch.solr.exceptions.SolrServiceException: Error while creating remote solr core. Status: HTTP/1.1 400 Bad Request
     de.hybris.platform.solrfacetsearch.solr.impl.SolrServiceStandaloneImpl.registerRemoteCore(SolrServiceStandaloneImpl.java:570)
     de.hybris.platform.solrfacetsearch.solr.impl.SolrServiceStandaloneImpl.getRegistredServersForFacetSearchConfig(SolrServiceStandaloneImpl.java:895)
     de.hybris.platform.solrfacetsearch.solr.impl.SolrServiceImpl.getRegistredServersForFacetSearchConfig(SolrServiceImpl.java:161)

solr-log

 org.apache.solr.common.SolrException: Error CREATEing SolrCore 'master_Reseller': Could not create a new core in /hybris/configs/solr/server/solr/./cores/master_Reseller/as another core is already defined there
     at org.apache.solr.handler.admin.CoreAdminHandler.handleCreateAction(CoreAdminHandler.java:662)
     at org.apache.solr.handler.admin.CoreAdminHandler.handleRequestInternal(CoreAdminHandler.java:214)
     at org.apache.solr.handler.admin.CoreAdminHandler.handleRequestBody(CoreAdminHandler.java:194)
     at org.apache.solr.handler.RequestHandlerBase.handleRequest(RequestHandlerBase.java:143)
     at org.apache.solr.servlet.HttpSolrCall.handleAdminRequest(HttpSolrCall.java:675)
     at org.apache.solr.servlet.HttpSolrCall.call(HttpSolrCall.java:443)
     at org.apache.solr.servlet.SolrDispatchFilter.doFilter(SolrDispatchFilter.java:210)
     at org.apache.solr.servlet.SolrDispatchFilter.doFilter(SolrDispatchFilter.java:179)

What causes this error and how can I fix it?

Regards

Andy