How to make work the solr core, generated by nutch for TYPO3?

I try to use a solr core thats generated by nutch version 1.16, that is included in solr version 7.7.3 and works fine so far in a TYPO3 version 9.5. But when I search I get the message "Search is currently not available." . I think that I have to configure the schema.xml, but I couldn’t fix this issue. Has anyone an idea how to make work the core for TYPO3?