The PDF version output by LaTeX is set by `\pdfminorversion` and this also sets the newest PDF version that LaTeX can use via `\includegraphics`. If `\pdfminorversion` default or setting is too low, by default LaTeX only issues a warning like:

PDF inclusion: found PDF version <1.7>, but at most version <1.5> allowed

and the PDF-input graphic will be missing. The too-old default PDF version of LaTeX is increasingly becoming an issue as PDF creation tools are rightfully increasing their default PDF output version from the ca. 2003 PDF v1.5 specification.

## Fix

To mitigate these issues, we do two things near the top of each project’s main LaTeX file:

1. create an error if the current PDF version is too old

``````\pdfinclusionerrorlevel=1
``````
2. set the default PDF version to ca. 2008 PDF v1.7

``````\pdfminorversion=7
``````

It’s OK for these PDF configuration lines to come after LaTeX directives.