macOS Sierra: If an app freezes or quits unexpectedly
There are several suggestions to try.
If the app is frozen and unresponsive, force quit the app (you may lose unsaved changes). Choose Apple menu > Force Quit, select the app in the dialog that appears, then click Force Quit.
If the app quit, reopen it by clicking Reopen in the dialog that appears.
Restart your Mac by choosing Apple menu > Restart.
Read the app’s documentation to see whether it’s compatible with your version of macOS.
Open another file in the app. There may be a problem with the original file.
Check for updates to your software.
Disconnect any peripheral devices you just connected (for example, a printer). They may not be compatible with your version of macOS.
Uninstall any app plug-ins or enhancements from other manufacturers.
If you recently updated the app or macOS, a plug-in or enhancement you installed may no longer be compatible.
Use Apple Diagnostics or Apple Hardware Test. These tools can tell you if hardware you installed, such as additional memory, is incompatible, improperly installed, or defective.