For anyone having to maintain a CF9 server with a javax error. Here is a local server running on port 52256 with box cfengin@9 aka 9.0.2+282541
You might get this in firebug:
Turning on Robust Exception Information, you might get a few different javax depending on the type of http request. For example at one point, it displayed javax/transaction/Synchronization
Found the solution to this at https://github.com/bobsilverberg/BlogPosts/blob/master/CF9ORMTomcat.cfm
Or directly, download this zip file, change the extension to .jar, and put it in the cf9 lib folder.
Downloading the file and adding it to my commandbox local lib folder translates to .Commandbox/server/[dynamic folder name]/adobe-9.0.2.282541/web-inf/lib/
Did the trick for me.