Any chance of an answer on this, I have the same problem (DW-CS5) after OS X 10.8 upgrade. FileMerge (the app that used to open), still exists in a different location and works fine. Also, /usr/bin/xcrun still exists which is defined as the file compare utility (linked from /usr/bin/opendiff). However since I don't know what params to feed it I don't know what's broken, never mind how to fix.

Please respond someone (Adobe?) will this be fixed, does the problem exist in DW-CS6?

It's a very useful tool

Thanks,

Maybe someone else upgrading to ML with DW CS5 can confirm the problem

Also someone on ML and DW CS6 confirm or deny problem

nm

Using Mountain Lion as well and encountered the same issue with DW 5.5.

Solution I found was to use use the path to diffmerge shell script (when using diffmerge), instead of to the actual application (.app).

In my case, that was "Macintosh HD:usr:bin:diffmerge". I began to use the steps here (http://xaviesteve.com/3096/compare-files-with-dreamweaver-in-mac-osx-s tep-by-step-guide/), but found that the script already existed.

Hope that helps.

One other thing I was thinking was if GateKeeper could be affecting the launching of one application by another?

Sometime back, I had changed my setting to allow applications from anywhere to run; while waiting for some trusted providers to get their non app store apps signed.

nauticalmac, if you havent already, maybe see if that makes a difference?

A little late to the thread.

I'm using CS6 on MBP OS 10.7.5 (Lion).

Latest version of Testwrangler puts an alias in usr/bin. The original twdiff is in TextWrangler.app>Contents>Helpers.

In DW Preferences, File Compare, select the usr/bin/twdiff alias. The result in the File Compare field will be the real location.

YM