ON a WordPress site, a plugin that I am using makes use of, jquery.cookie.js. My hosting provider makes use of mod_security prevented jquery.cookie.js from being server and resulted in error 406.
As I looked at the failure in the Chrome development tools network log, I saw that the line in questions was,
http://neuron-tech.ca/wp/wp-content/plugins/soldpress/lib/jquery.cookie/jquery.cookie.js?ver=1.3.1 all in bold red.
The solution was to contact the hosting provider and they modified the mod_security rule for this on my website.
As I looked at the other JavaScript files in the Network log, they all had ".js/?" followed by the version of the JavaScript code.
Why is this done, what is the purpose of adding the version number after the "?"? If I do it, I end up with the JavaScript in the browser as plain text. Is this some kind of technique to verify thta the JavaScript has successfully been served?
Appending a ? to a JavaScript (or CSS or Image, ...) file has nothing to do with modsecurity.
It is done to "bust" the browser cache, i.e. to force the user's browser to load a new version of a file of the same name (apart form the 'ver'-parameter) and not reuse the one from the cache.
Also see: Cache busting via params