LaTeX.org

Even though this thread is 11 years old, it appeared as the 3rd result in my google search for this problem.

My solution to this was pretty simple:

I had

\usepackage[citestyle=numeric,style=numeric,backend=bibtex,sorting=none]{biblatex}
\nocite{*}
...
\cite{..}
\cite{..}
...
\backmatter ...