Language problems with biblatex and babel

Question

I am trying to use biblatex with IEEEtran and babel, however I am having an error: Package babel Error: You haven't defined the language ENGLISH yet.. With regular Bibtex everything works as usual. The MWE is the following:

\documentclass[english]{IEEEtran}

\usepackage{babel}
\usepackage[utf8]{inputenc}
\usepackage[T1]{fontenc} 

\usepackage[strict,autostyle]{csquotes}
\usepackage[style=ieee,backend=bibtex]{biblatex}
\bibliography{/usr/local/texlive/2012/texmf-dist/doc/latex/biblatex-ieee/biblatex-ieee.bib}

\usepackage{blindtext}

\begin{document}

\Blindtext

\nocite{*}
\printbibliography

\end{document}

Answer 1

The error seems indeed to be caused by the combination biblatex/babel/IEEEtran -- your example (with an appropriate .bib file) works with the article class. A workaround is to fake an ENGLISH (uppercase) dialect for the english language.

\documentclass[english]{IEEEtran}

\usepackage{babel}

\makeatletter
\adddialect\l@ENGLISH\l@english
\makeatother

\usepackage[utf8]{inputenc}
\usepackage[T1]{fontenc} 

\usepackage[strict,autostyle]{csquotes}
\usepackage[style=ieee,backend=bibtex]{biblatex}
\addbibresource{biblatex-examples.bib}

\usepackage{blindtext}

\nocite{*}

\begin{document}

\Blindtext

\printbibliography

\end{document}

Answer 2

The problem is that IEEEtran.cls changes the meaning of \markboth applying yet another \MakeUppercase, to which

\protect\foreignlanguage{english}{%
  \protect\bbl@restore@actives\MakeUppercase{\refname}}

is passed, resulting in LaTeX trying to do

\foreignlanguage{ENGLISH}

which gives the error. This is caused by \printbibliography, but is not a responsibility of biblatex, only by a not so wise redefinition of \markboth

One can notice that \refname is already passed to \MakeUppercase.

You have two choices:

1. change the bad redefinition of \markboth:

   \makeatletter
   \def\markboth#1#2{%
     \def\leftmark{\@IEEEcompsoconly{\sffamily}#1}%
     \def\rightmark{\@IEEEcompsoconly{\sffamily}#2}}
   \makeatother
   

   The IEEEtran definition has \MakeUppercase{#1} and \MakeUppercase{#2}.

2. enable a fake ENGLISH language referring to english:

   \makeatletter
   \let\l@ENGLISH\l@english
   \makeatother
   

Just put one of the two pieces of code in the preamble of your document. Probably the second one is the safest.