Downloaded app won't open because it is from an unidentified developer I have download photo express mac version on my MacBook Pro and it won't open it said can't opened because it is from an unidentified developer. But I'm using there mac download so what do I do so I can get it to work
I would appear that for some reason the developer of Photo Express is not registered with Apple as an identified developer. 

To get it to install you will need to go to System Preferences and change the default setting for application downloads...

System Prefs-> Security And Privacy -> and select Allow apps downloaded from Anywhere.



Remember to set the value back to Mac App Store and identified developers afterwards.