"Package inputenc Error: Invalid UTF-8 byte sequence" on the .bbl file

Question

Package inputenc Error: Invalid UTF-8 byte sequence. \bibinfo{author}{Budulan, �.}

I got the above error where it has something to do with the .bbl file.

Upon checking, the line has this error:

\bibinfo{author}{Budulan, �.}, \bibinfo{author}{Burceanu, E.},

The author's name is spelt as Budulan, Ştefania. See the letter S.

What does it mean and what should I do?

Answer 1

BibTeX cannot deal with Unicode characters outside the US-ASCII range. Often that does not become apparent when you just look at the output in the document, since BibTeX usually just passes the characters thorough as they are. But when you ask BibTeX to perform string manipulation or sorting it can become painfully obvious that BibTeX doesn't know how to deal with non-US-ASCII characters. Shortening of first names is one of those operations.

I did not manage to reproduce the exact error from your question, but here is an example of Ş misbehaving twice. In BibTeX you'll have to use the macro escape {\c S} instead. See also How to write “ä” and other umlauts and accented letters in bibliography?.

\documentclass[british]{article}
\usepackage[T1]{fontenc}
\usepackage[utf8]{inputenc}
\usepackage{babel}
\usepackage{csquotes}

\usepackage{natbib}
\bibliographystyle{abbrvnat}

\begin{filecontents}{\jobname.bib}
@article{budulan:bad,
  author  = {Budulan, Ştefania},
  title   = {Bad -- Unicode (Ş S)},
  year    = {1980},
}
@article{budulan:good,
  author  = {Budulan, {\c S}tefania},
  title   = {Good -- macro escape ({\c S} S)},
  year    = {1980},
}
\end{filecontents}


\begin{document}
\cite{budulan:bad,budulan:good}
\bibliography{\jobname}
\end{document}

With biblatex you could use Biber as a backend, which deals with Unicode out of the box.

---

As David points out in the comments, the symptoms in the question could be explained by using non-ASCII characters and a different (assumed) encoding for the .bib file and .tex file (latin2 for the .bib and UTF-8 for the .tex file). With BibTeX you need to make sure that the .bib and .tex file encodings match. But as I said before, BibTeX doesn't really accept anything but US-ASCII.

If your .bib file is written by a third-party tool, you need to configure that tool to use a compatible encoding, but you should also instruct the tool to use macro-escapes for non-ASCII characters.