The app has been modified or damaged
The app has been modified, and its code does not match the original signed code. The app may be broken or corrupted, or it may have been tampered with. If you think that an app has been damaged or tampered with, you should delete it by dragging it to the Trash.
Some apps and tools, such as AppleScript or JavaScript applications and some legacy tools, modify themselves after signing. These types of apps cannot be opened unless the settings in the General pane Security & Privacy preferences is set to allow apps downloaded from anywhere.
Choose Apple menu > System Preferences, click Security & Privacy, then click Privacy.
Open the General pane of Security & Privacy preferences for me
For more information about protecting your Mac from harmful software, see Protect your Mac from malware.