Sharelatex generates only dot on on first reference, instead of reference

Question

I'm trying to compile a LaTex file online with sharelatex. It works fine, but on top of my generated references the first seems to be broken. It only shows " [1] ." . All other 25 references seem to be fine. It is also awkward that the [1] reference doesn't even appear in the document anywhere.

I'm not sure, but I think this warning might be connected, since it is the only one I get:

/usr/local/texlive/2017/texmf-dist/tex/latex/biblatex/blx-bibtex.def Package biblatex Warning: Using fall-back BibTeX(8) backend: functionality may be reduced/unavailable.

The bibilography is generated with \printbibliography

Answer 1

I found a solution after looking on the right forum: https://tex.stackexchange.com/questions/365060/warning-using-fall-back-bibtex8-backendbiblatex-functionality-may-be-redu

I had to use \usepackage[backend=bibtex,style=numeric,sortcites,natbib=true,sorting=none]{biblatex} instead of %\usepackage[backend=bibtex, style=numeric]{biblatex}

I still don't really get why it works now. The warning is still displayed, but the problem with the first reference is gone. When i try to use biber with \usepackage[backend=biber, style=numeric]{biblatex} it simply doesn't output any table of references.

edit:

It seems what I thought fixed it here didn't, but just hid the broken reference in between fine ones. I made a mistake in the .bib file, one closing bracket } to much. I didn't notice it before because I didn't know how to assassinate the broken reference with its counterpart in the .bib file.