Missing $ inserted issue

What Werner and Gonzalo said would indeed be very helpful. From the limited info given however, I guess LaTeX struggles with the _ in the line, since it normally sees that as a subscript indicator and only expects it in math mode.

A very short solution (and impossible to say if that works without taking a look at the offending code) is to escape the underscore ("_"), by placing a backslash before it.

The problem is the underscore _ in a doi. It occurs in line 190 of the LaTeX file (or in the .bbl) not in the .bib file.

Search for 10.1007/978-0-387-68772-8_18 in your .bib file. You can use the url package and enclose the entry in url{10.1007/978-0-387-68772-8_18} to avoid the error. Alternatively you can use a bibtex style that knows about dois.

Another solution could be to drop the whole "_18" as it says just "chapter 18". If you write "10.1007/978-0-387-68772-8" rather than "10.1007/978-0-387-68772-8_18" the reader will still be referred to the right book, but not to chapter 18 within it.

Try using in the preamble usepackage{url}. This should clear the problem.

To get rid of the underscore ("_"), you can use shortdoi.org and doi:10/djzjd6 instead of doi:10.1007/978-0-387-68772-8_18, which is also nice when your readers need to type the doi from a printed version of your thesis instead of being able to click at it in an electronic document.

Another future-proof answer, albeit rather tedious, is suggested here:

Change all occurrences of _ in the URL field of your .bib file to their html character code equivalent %5F

usepackage[strings]{underscore}

If you are getting this issue when submitting to arXiv, one possible source of the problem may be that you are trying to use a .bib file as a .bbl.

While renaming the .bib to .bbl is pretty silly in retrospect, that's what I did (not understanding that they are different). And then I ran into these errors. You need to submit the .bbl that is generated when you compile on your machine (or, in my case, download the .bbl file produced by ShareLaTeX online). The format of the .bbl is different from the .bib and the references will not show up correctly or be cited correctly.

From a similar question, the answer that worked for me was adding

usepackage{hyperref}
usepackage[T1]{fontenc}

to the preamble. (Or usepackage[hidelinks]{hyperref} to avoid the ugly boxes.)

Credit to Ulrike Fischer and CGFoX

In my case there was a problem with the encoding. I used usepackage[macintosh]{inputenc}.

I solved the problem by switching to usepackage[utf8]{inputenc} but i also had to update the encoding of my files by using iconv.

The short way:

1. open "*.bib" file

2. Replace:

        "-" >>>> "_"
        "&" >>>> "&" (specially check in the links)
        "" >>>> "" (specially check in the links)
   

3. Delete all temporary files: In Texmaker:

        Tools -> Clean
        Bibliography -> Clean
   

4. You are done! Very Important Note: You do not need any extra package, so do not use them, in order to prevent further problems.