Biblatex biblography prints all caps letters when using UTF8 special characters

I use biblatex with a biber backend and the \usepackage[utf8]{inputenc} package. For some reason, references in my .bib file that contain special characters are printed in all-caps in my bibliography.

I tried replicating the effect with a MWE, however every version I tried printed the bibliography in a correct way. Does anyone know of a combination of packages that could cause this behavior?

EDIT: MWE replicating the effect

\RequirePackage{filecontents}

\begin{filecontents*}{mybib.bib}
@book{test1,
address = {City},
title = {{Öffentlichkeit}},
publisher = {Doe, Jane},
author = {Doe, Jane},
year = {1937}
}

\end{filecontents*}

\documentclass[
12pt
]{book} % The class file specifying the document structure

% Set the values for the bibliography
\usepackage[
style=apa,
backend=biber,
isbn=false,
url=true,
doi=true,
natbib=true,
eprint=false,
hyperref=true,
backref=false,
firstinits=false
]{biblatex}

\usepackage[utf8]{inputenc}
\usepackage[autostyle=true]{csquotes} % Required to generate language-dependent quotes in the bibliography
\usepackage{xpatch}

% Set language
\DeclareLanguageMapping{american}{american-apa}

\addbibresource{mybib.bib}

\addbibresource{mybib.bib}

\begin{document}

\textcite{test1}

\printbibliography
\end{document}

• Ok, placing the special characters inside extra curly brackets solves the problem, although I still do not understand what causes this behavior. May 14 '21 at 13:20
• It is very, very hard to say anything without seeing code that reproduces the undesirable output. If you have a document that does reproduce the undesirable output, it should be possible to turn (a copy of) it into a minimal example by removing as much code as possible while still retaining the undesirable output. Generally with biblatex there should not be a need to protect non-ASCII chars with curly braces, but with BibTeX (where you officially can't use non-ASCII chars) you have to surround the macros-escapes with braces (tex.stackexchange.com/q/57743/35864). May 14 '21 at 13:38
• I added a MWE replicating the effect May 14 '21 at 13:56
• I see no problem with your example (with and without the braces) in a current texlive.. Show your log-file and the blg file. May 14 '21 at 15:38

1 Answer

The issue does not occur when one runs the MWE as is with a current version of biblatex. The issue can, however, be reproduced if one switches to the legacy chase changing method with casechange=latex2e, (which was the - unchangeable - default in older versions [<=v3.14] of biblatex).

\documentclass{article}
\usepackage[T1]{fontenc}
\usepackage[autostyle=true]{csquotes}
\usepackage[backend=biber, style=apa, casechanger=latex2e]{biblatex}

\begin{filecontents*}{\jobname.bib}
@book{test1,
author    = {Doe, Jane},
title     = {{Öffentlichkeit}},
year      = {1937},
publisher = {Pub \& Co.},
address   = {City},
}
\end{filecontents*}
\addbibresource{\jobname.bib}
\begin{document}
\textcite{test1}

\printbibliography
\end{document}


It is related to the problems with the case changer discussed in https://github.com/plk/biblatex/issues/459.

A workaround would be to brace only the first letter of the word and not the entire word

@book{test1,
author    = {Doe, Jane},
title     = {{Ö}ffentlichkeit},
year      = {1937},
publisher = {Pub \& Co.},
address   = {City},
}


With German titles it would in general be preferable to mark the titles up as German to avoid any case changing completely

@book{test1,
author    = {Doe, Jane},
title     = {Öffentlichkeit},
year      = {1937},
publisher = {Pub \& Co.},
address   = {City},
langid    = {ngerman},
}


From version 3.15 (2020-08-16) onwards, biblatex uses expl3 case changing functions (if the LaTeX kernel is sufficiently modern and the document is encoded in UTF-8). Those case changing functions are in general more robust and do not have this issue. Update your TeX distribution if possible.

• Thank you very much May 16 '21 at 11:17