Invalid or undefined BibTeX entry key in file ...

[dbitouze]

(This is a follow up of plk/biblatex#818.)

With biblatex v3.17 and biber v2.17, the following MCE:

\begin{filecontents}[overwrite]{\jobname.bib}
@periodical{0,
  issuetitle = {Issue Title},
}
@article{0-art,
  title={Article's Title},
  author={Last, First},
  crossref={0}
}
\end{filecontents}

\documentclass{article}
\usepackage{biblatex}
\addbibresource{\jobname.bib}
\begin{document}
\autocite{0-art}
\printbibliography
\end{document}

gives the following warning during the biber compilation:

WARN - Invalid or undefined BibTeX entry key in file
'/tmp/biber_tmp_Std3/5a453152acdb3e2485a9d6a17b3ec69c_1859422.utf8', skipping ...

and the given file is removed just at the end of the compilation so cannot be checked.

[plk]

Yes, this isn't a valid entry key according to the underlying btparse library - it can't begin with a number as far as I remember.

[dbitouze]

Yes, this isn't a valid entry key according to the underlying btparse library - it can't begin with a number as far as I remember.

Indeed, thanks.