/usr/share/texlive/texmf-dist/tex/latex/biblatex/blx-bibtex.def:
Package biblatex Warning: Using fall-back BibTeX(8) backend:
(biblatex) functionality may be reduced/unavailable.
EXAMPLE:
\usepackage[backend=bibtex,style=authoryear,natbib=true]{biblatex}
\addbibresource{Elyssesbib.bib}
\usepackage[autostyle=true]{csquotes}
\begin{document}
\...... rest of doc.
biblatex, usebiberas a backend, notbibtex8. – Bernard Jul 26 '17 at 23:17biblatexfeatures. BibTeX is supposed to be used only in legacy documents and if absolutely necessary. That said, if everything works fine for you at the moment, you don't have to change. – moewe Jul 27 '17 at 05:48