we have identified this as a compatibility issue with Security Assist and are working on a fix.
In the mean time, you can disable security assist in the extension manager t o get around the error.
Your friends over here at WebAssist! These Dreamweaver extensions will assist you in building unlimited, custom websites.
These out-of-the-box solutions provide you proven, tested applications that can be up and running now. Build a store, a gallery, or a web-based email solution.