Recently I got to list a bunch of BibTeX references in a document. The BibTeX entries were fetched from Crossref API and they all include a DOI field. When I tried to compile the document, an underscore (_) in one BibTeX entry caused the compiler to complain about using subscript in a non-math environment:
Missing $ inserted.
...
I've inserted a begin-math/end-math symbol since I think you left one out. Proceed, with fingers crossed.I found in an Overleaf Guide that this might be caused by an underscore in the URL field and could be fixed by \usepackage{url}. This didn’t work. So I thought if there’s a URL package there could also be a DOI package, too. It turned out to be true. \usepackage{doi} fixed my problem. In the package page, it even mentions specifically it’s meant to fix the troublesome characters like an underscore.
