title: The Solr core could not be accessed
body: <p>I install search_api Version: 8.x-1.14
  and search_api_solr Version: 8.x-3.3 and solr-7.7.2 on my server.
  then do the following steps as mentioned in the documentation. </p>
  
  <p>Any advice, Thanks</p>
  
  <ul>
  <li>mkdir /server/solr/drupal</li>
  <li>mkdir /server/solr/drupal/conf</li>
  <li>touch drupal/core.properties</li>
  <li>echo "name=drupal" > /server/solr/drupal/core.properties</li>
  <li>Create a Search API Server according </li>
  <li>Extract the config.zip that create for me when I setup the Search API Solr Search module to the conf directory of my core.</li>
  <li>bin/solr start -force</li>
  </ul>
  
  <p>before start the solr server (without -force ) this message appears: </p>
  
  <pre><code>*** [WARN] *** Your open file limit is currently 1024.
   It should be set to 65000 to avoid operational disruption.
   If you no longer wish to see this warning, set SOLR_ULIMIT_CHECKS to false in your profile or solr.in.sh
  *** [WARN] ***  Your Max Processes Limit is currently 31862.
   It should be set to 65000 to avoid operational disruption.
   If you no longer wish to see this warning, set SOLR_ULIMIT_CHECKS to false in your profile or solr.in.sh
  WARNING: Starting Solr as the root user is a security risk and not considered best practice. Exiting.
           Please consult the Reference Guide. To override this check, start with argument '-force'
  </code></pre>
  
  <p>these errors appear when I create the server on drupal:</p>
  
  <pre><code>Server Connection   The Solr server could be reached.
  Core Connection The Solr core could not be accessed. Further data is therefore unavailable.
  Configured Solr Version 7.0.0
  Detected Solr Version   7.7.2
  Additional information  An error occurred while trying to retrieve additional information from the Solr server: Solr endpoint http://x.x.x.x:8983/ internal error.
  </code></pre>
  
  <p>and on solr logging: </p>
  
  <pre><code>org.apache.solr.common.SolrException:org.apache.solr.common.SolrException: Could not load conf for core drupal: Error loading solr config from /var/www/solr-7.7.2/server/solr/drupal/conf/solrconfig.xml
  </code></pre>
  
  <pre><code>org.apache.solr.common.SolrException: undefined field hash
  </code></pre>
  
  <pre><code>Error waiting for SolrCore to be loaded on startup
  </code></pre>
  
  <pre><code>HttpSolrCall
  null:org.apache.solr.core.SolrCoreInitializationException: SolrCore 'drupal' is not available due to init failure: Could not load conf for core drupal: Error loading solr config from /var/www/solr-7.7.2/server/solr/drupal/conf/solrconfig.xml
  </code></pre>
  
  <p>I try to create a solr user because I read that running the Solr as root cause this issue. but many steps I can't do due to denied permissions when I run it as solr user.</p>