ISO date goes over the end of the line

[mdesharnais]

Hi,

I use ISO date format for my bibliography and some references have a date field that extend over the end of the line.

Is there a way to allow LaTeX, as a last resort, to break the date between the year, or month, or day fields? Or is there another recommended way to make the line fit?

[moewew]

With standard biblatex these date strings are breakable as a last resort.

\documentclass[british,a4paper]{article}
\usepackage[T1]{fontenc}
\usepackage[left = 20mm, right = 20mm, showframe,]{geometry}
\usepackage{babel,csquotes}
\usepackage[backend = biber, alldates=iso,]{biblatex}

\addbibresource{biblatex-examples.bib}

\begin{document}
Lorem \autocite{ctan}.

\printbibliography
\end{document}

Generally speaking, however, line breaking is tricky in the bibliography and you can always run into bad breaks. There is a number of general things you can do to improve/modify line breaking, but no general method guarantees that you never see bad breaks. See https://tex.stackexchange.com/q/442308/35864.