Having issues with the popup calendar feature after CF11 update 12 or CF2016 update 4? There's a fix
The issue is discussed in a CF bug entry, CF-4198570, but since I've had a couple of customers recently ask for help on it, I thought I'd bring it up in a blog post here.
TLDR: you just need to obtain a special hotfix jar file, either the one for CF11 or the one for CF2016. (If you find that just clicking the link shows you gibberish in your browser, right-click the link and save the file instead.)
Put that saved jar in the lib\updates folder for your instance(s), and restart CF, and the problem will go away.
For more on the matter, as always, see below. :-)