Error "Exception while pinging the index server" occurring in MethodServer log in Windchill PDMLink

• There is error message in MethodServer log:  

  Exception while pinging the index server

• Troubleshooting steps for exception while pinging the index server/solr server
• The Index search function is not available, an attribute search has been used. The search results may not contain all of the object you expected
• Advanced Search is not working after doing the rehost
• Error message in Foreground Method Server or Background Method Server log: 

  ERROR [pool-5-thread-1 OR IndexQueue2] wt.index.StandardIndexPolicyManager  - Exception while pinging the index server
  org.apache.solr.client.solrj.SolrServerException: Server refused connection at: http://<FQDN>:8085/solr/wblib

• The search results is not showing all the objects, the following error is reported:

ERROR [pool-4-thread-1] wt.index.StandardIndexPolicyManager - Exception while pinging the index server
org.apache.solr.client.solrj.SolrServerException: IOException occurred when talking to server at: XXXXXXX:8085/solr/wblib
at org.apache.solr.client.solrj.impl.HttpSolrClient.executeMethod(HttpSolrClient.java:695)
at org.apache.solr.client.solrj.impl.HttpSolrClient.request(HttpSolrClient.java:266)
at org.apache.solr.client.solrj.impl.HttpSolrClient.request(HttpSolrClient.java:248)
at org.apache.solr.client.solrj.SolrClient.request(SolrClient.java:1290)
at wt.index.service.SolrServiceImpl.pingSolr(SolrServiceImpl.java:144)
....
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
at java.lang.Thread.run(Thread.java:748)
Caused by: javax.net.ssl.SSLException: Unrecognized SSL message, plaintext connection?