ERROR: "Missing } inserted" in bib file

Question

In running my file I obtain this error pointing and redirecting me to the final line of the bbl file (Missing } inserted. \end{thebibliography})

I checked previous stackexchange topics and there DO NOT appear to be any 'graphical' parentheses (i.e. "{" or "}"). Moreover I never tinkered with the bbl file and I do not kow how I got an error there.

I run several times the sequence: LaTeX, BibTeX, LaTeX, LaTeX.

I work through TeXstudio, version 2.12.6.

Thanks a lot for the help, Mark

Answer 1

An example such as the following will produce the error that you state.

The first run through latex will give no error, bibtex will give no error but the generated .bbl file will have code that generates a mis-matched { that in itself causes no error at that point but when \end{thebibliography} is reached LaTeX complains that it is trying to close the wrong kind of group as it is expecting a } so you get

! Missing } inserted.
<inserted text> 
                }
l.11 \end{thebibliography}

? 

Note that a simple mis-matched { in a bib entry would already be detected by bibtex which would give an error and detect the entry but as shown here it is possible to have constructs that allow a mis-matched brace to slip past bibtex's checks.

So in your real document look for mis-matched braces in the generated bbl file and once found correct the bib entry that produced them.

\begin{filecontents}{\jobname.bib}

@misc{abc,
title="title one",
author="yo{\iffalse}\fi u",
publisher="someone"}

@misc{xyz,
title="title two",
author="me",
publisher="zzz"}

\end{filecontents}
\documentclass{article}

\begin{document}
something about \cite{abc} and also \cite{xyz}

\bibliographystyle{plain}
\bibliography{\jobname}



\end{document}

Answer 2

I just had to debug this issue. Since many different things could cause this, the general strategy is to repeat the following steps:

1. Remove a part of your document's preamble.

2. Delete the .bbl and .aux files.

3. Rerun (pdf)latex, bibtex, (pdf)latex.

If you remove the whole preamble, the error should go away. So, eventually, this algorithm should converge to the offending statement.

In my case, the offending part was this workaround that I introduced into the preamble in the meantime.