I just upgraded to the new beta 2 and receive this error when opening cfbuilder/eclipse. I also get this error when I tried to delete and add the only localhost server I've got.
CFBuilder beta 2
Did you have Beta 1 installed previously? If so then I had a similar issue. I then dug around and found that there is an uninstaller under the eclipse folder "\Uninstall Adobe ColdFusion Builder plugins"
So I ran this, and then made sure i removed ALL folders and JARs in the plugins folder that begin with "com.adobe"
The resintalled Beta 2. Then my server's started working again.
Although on a side issue I still receive: "Unable to fetch server mappings."
Hope this helps
If anyone's looking for instructions to upgrade from ColdFusion Builder Beta 1 plug-ins to ColdFusion Builder Beta 2 plug-ins, you may want to see this Help topic in the ColdFusion Builder Install Guide: