Fulltext search in the web client returns errors like this:
The remote server returned an error: (404) Not Found.
If you go to the Solr address you can find in Administration>system>Data connections>Fulltext server connections> Default Solr Connection and open it on the browser you wil receive a message like this:
There are no SolrCores running.
Go to the configuration of the file cabinet and go to fulltext options and click on 'Deploy Fulltext application'.