During the last days I am really stressed because I face a problem with my References that I never had before. With the following, I try to generate my bibliography but I either get the error "\providecommand\NAT@force@numbers{}\NAT@force@numbers", or I get my document with question marks instead of bibliography names/dates.

Any ideas how to spot the issue which causes me this and fix it?

here are my two .bib files

I do not want to use natbib with numbers but with names and I do not understand the reason why I have this issue. I read similar issues but I can not spot any missing dates on my files which previously were fine and that is why I am confused.

P.S. I show you all the packages that I use in case something else causes the problem.

\usepackage[colorlinks = true,
linkcolor = blue,
urlcolor  = blue,
citecolor = blue,
anchorcolor = blue]{hyperref}

%\usetikzlibrary{shapes.geometric, arrows}




        \title{\vspace{-3.0cm}\rule{\textwidth}{1pt}\\title here \\\vspace{1.0cm}\rule{\textwidth}{1pt}\\{\Large Probation Report}}
    \author{author here\thanks{department here}}


    \section{bla bla}
    bla bla bla bla  \citep{holling_resilience_1973,gunderson_ecological_2000} bla bla bla  \citep{gunderson_ecological_2000}. bla bla bla bla bla bla  \citep{achard_areas_2006, alkama_biophysical_2016, appenzeller_new_2015, bergeron_ecosystem_2017, berner_plant_2013,brown_once_2012, chapin_global_2004, forkel_trend_2013, forkel_codominant_2015, furyaev_effects_2001, lucht_terrestrial_2006, rydgren_disturbance_2004, jasinski_creation_2005, soja_climate-induced_2007, scheffer_thresholds_2012, williams_who_2011, young_climatic_2017, vygodskaya_ecosystems_2007, tanja_air_2003}. 

\section{Supplementary material}

  • 2
    Why are you using two bibliographystyle commands? (plainnat and apalike)? Nov 16, 2018 at 9:20
  • @UlrikeFischer apologies, I do not, it is just a mistake here, I will edit my question. Thanks.
    – geo_dd
    Nov 16, 2018 at 9:32

1 Answer 1


In my experience, this error is caused by bibliographic references that are missing a year. Loading the bib files into JabRef and sorting by year should help you to identify the problematic entry.

  • I know that missing dates and authors may cause this problem. I will try to load them in zotero and check them.
    – geo_dd
    Nov 16, 2018 at 9:48
  • Thank you very much. I was looking for no date references in TexStudio and missed two of them. It is better to do it through zotero directly. Thank you!
    – geo_dd
    Nov 16, 2018 at 11:56

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