Run Viber on Mac OS 10.10 Yosemite Beta - Fix
Changing a plist file will fix Viber and make it work on Yosemite, as this version of Mac OS X is still a beta and there’s currently no working version of Viber available for it. Don’t forget to backup the plist file before editing.
Right click on the Viber application and Show Package Contents, then in the contents folder, edit info.plist with a code editor app like Sublime Text, and finally, in the following lines change 4 to 5:
<key>CFBundleShortVersionString</key>
<string>5</string>
<key>CFBundleVersion</key>
<string>5.2.0</string>