Steps to replicate the issue (include links if applicable):
Open an article (in my case, on Microsoft edge)
open article menu and click "Download as PDF"
Get bad request error

What happens?:
Gives an error page "bad request"

What should have happened instead?:
The article should have downloaded as a PDF

Software version (on Special:Version page; skip for WMF-hosted wikis like Wikipedia):

Other information (browser name/version, screenshots, etc.):
Microsoft Edge (beta)