Using texlive 2016 and TeXstudio 2.12.6, the following example worked:
\documentclass{article}
\usepackage{graphicx}
\begin{document}
\includegraphics[resolution=300]{figure.png}
\end{document}
Then I did this:
tlmgr update --self
tlmgr update --all
Now, the same example gives the following error:
! Package keyval Error: resolution undefined.
How can I figure out what changed, and in which package(s)?