"Undefined citation" error

Question

I have this in references.bib ​

@online{sep,
    author = "Barry W. Boehm",
    title = "Seven Basic Principles of Software Engineering",
    year = "2008",
    url = "http://sunset.usc.edu/TECHRPTS/1983/usccse83-500/usccse83-500.pdf",
    urldate = "2018-11-14"
}

​​ ​ Then I have this in the main .tex: ​

\usepackage[backend=biber,style=authoryear-ibid,sorting=ynt]{biblatex}
\addbibresource{references.bib}

\begin{document}

\maketitle

\tableofcontents
​
\section{SE}

\parencite{sep}

\printbibliography

\end{document}
​

But this gives me an "undefined citation" error.

I'm using TeXmaker on to of MacTeX.