A LaTeX document that uses BibLaTeX was compiling without errors on Ubuntu 12.04 using Vim-LaTeX. When I changed to Ubuntu 14.04, compiling the same document gave this warning:
LaTeX Warning: Empty bibliography on input line 728.
The resulting PDF had no citations and no bibliography!
In Ubuntu, the TeX-Live distribution is typically used for LaTeX compilation. In the years since the TeX-Live of Ubuntu 12.04, BibLaTeX has switched from bibtex to biber as its backend. Also, Vim-LaTeX has not been updated in these years and it still uses bibtex. This was causing the error.
First, we install biber:
$ sudo apt-get install biber
Next, using the clues given by Paul I forked Vim-LaTeX and fixed it to use biber. To use this fork:
$ git clone https://github.com/ashwin/vim-latex.git
Compiling the LaTeX document using Vim-LaTeX now should not have this error and the bibliography should be produced. 😊