URGENT: Adobe print pdf exporting zero bytes

Did you just update to INDD 24?

Are you saving to your HD or a Server?

Try saving to an alternate location and or changing the file name.

I've already solved a similar problem by saving in IDML format, saving the IDML as INDD, and then I was able to export as a PDF from the new INDD document.

You might be able to find some information to answer the last of James' questions if you go to Window -> Utilities -> Background Tasks and try to export another PDF, and report what you see in the Background Tasks panel while the PDF tries and fails to export. 

What version of ID, and on what OS? There have been some reported problems with PDFs recently; the solutions seem to boil down to "update your OS" (mostly for MacOS), and "roll back your ID version to a prior, stable one."

There are, of course, other possibilities — have you tried various PDF settings, other documents, exporting to a local folder (not network or cloud), etc.? Are there any specific error messages, or does the export simply "conplete" without actually writing the output file?