tl;dr

The following snippet throws an exception in jQuery from version 1.8.3 and forward:

$('<div><a></a></div>').find(':not(:hidden) + c , d')

The exception reads:

Cannot read property '0' of undefined

When asking JSFiddle to use jQuery version 1.x/2.x, the message changes to:

Cannot read property 'length' of undefined

If appending the new element to another node, it works fine:

$('<div><a></a></div>').appendTo('<div>').find(':not(:hidden) + c , d')

More details

Testing in JSFiddle (http://jsfiddle.net/cpxbb/), it worked in jQuery 1.7.2 and started failing in jQuery 1.8.3.

The error message changed nature between 1.9.1/2.0.2 and the 1.x/2.x versions (JSFiddle does not currently have any specific versions above 1.9.1/2.0.2).

I debugged a bit through the minified version of 1.8.3, and it fails at a point where it tries to find tags based on the parentNode of the root element, which is a document-fragment for an unattached element.

The call that returned undefined is:

i.find.TAG("*", h && a.parentNode || a)

where a is the top element (the div in the example code).

An immediate work-around is to attach the node to a dummy-element before running the find operation.