dokuwiki\Exception\FatalException: Class refnotes_bibtex_mode contains 1 abstract method and must therefore be declared abstract or implement the remaining methods (dokuwiki\Parsing\ParserMode\AbstractMode::handle)

An unforeseen error has occured. This is most likely a bug somewhere. It might be a problem in the refnotes plugin.

More info has been written to the DokuWiki error log.