[Tex/LaTex] biblatex-chicago etoolbox error: Invalid boolean Expression


I am using bibtex as the backend for my biblatex bibliography but there seems to be some clash between it and the etoolbox package that I don't understand. This is on a fresh install of TeXlive 2014. The error only appears if the following conditions are met:

1: BibTeX is the backend
2: I am using biblatex-chicago (there's no tag for that – sorry!)
3: A bib entry is cited twice in the same paragraph

A minimal example follows (in which I have embedded the bibliography in the file for the sake of keeping it simple – doing it this way didn't change the error).


    address = {City},  
    edition = {1st},  
    title = {Help},  
    publisher = {A. N. Other},  
    author = {Smith, John},  
    year = {1970},  



\cite[732]{smith_john_1970} and \cite[732]{smith_john_1970}


Best Answer

If one does some digging in chicago-notes.cbx, in the definition for the cite bibmacro one finds

    test {\iffieldundef{shorthand}}%
    togl {blx@skipbiblist}%
    togl {cms@inheritshhand}%
    not test {\iffieldundef{crossref}}%

And indeed that seems to be the boolean expression that causes etoolbox to get the hiccups. All but one of these conditions are completely fine, the problem arises from togl {blx@skipbiblist}.

skipbiblist is - like its friendsskipbib and skiplab - a Biber-only option (unfortunately, skipbiblist is quite new and not documented in the docs, it is an extension of skiplos and works in similar fashion to its "friends", see p. 62 § Type/Entry Options of the biblatex documentation)

If you do not use Biber, but BibTeX or BibTeX8, the file biblatex1.sty is loaded (with Biber it would be biblatex2.sty), biblatex1.sty, however does not have a definition for blx@skipbiblist (it does provide one for blx@skipbib, blx@skiplos and blx@skiplab though - so it rather seems like a biblatex1 bug for me) and therefore the conditional is invalid for etoolbox, because blx@skipbiblist does not exist if you do not use Biber.

But I want a fix now!

There are two fixes for this issue

1. Use Biber

Just use Biber as your backend, enjoy all its functionalities and capabilities and get rid of this little bug; you merely have to pass backend=biber as loading-time option to biblatex/biblatex-chicago (and obviously have Biber installed and run it instead of BibTeX).

That is the preferred solution, see for example page 1 (!) of the biblatex-chicago documentation:

I also strongly encourage all users who haven’t already done so to switch to Biber as their backend; it has long been a requirement for the author-date styles, but it is now becoming indispensable for accessing all the features of the notes & bibliography style, as well.


2. Provide the missing toggle yourself

Just put


into your preamble.




\cite{wilde} and \cite{wilde}