Click Cancel to abort the attempt to open the file, or click the Choose Application or Search App Store button to select another application to open this file. If you click the Choose Application button, a dialog appears (conveniently opened to your Applications folder). Applications that OS X doesn’t think can be used to open the file are. Less secure apps can make it easier for hackers to get in to your account, so blocking sign-ins from these apps helps keep your account safe. If 'Less secure app access' is on for your account Because less secure apps can make your account more vulnerable, Google will automatically turn this setting off. Delete the app preference file. Plist files can become corrupt when a Mac shuts down or restarts unexpectedly or when an app freezes or crashes. As a result, the app may not open. When you delete a bad preference file, the Mac creates a new plist file that contains all the app's defaults automatically.

Allow Unsecure Apps Gmail

To quit (close) a Mac app normally, choose Quit from the app's menu in the menu bar, or press Command (⌘)-Q. If the app doesn't quit, follow these steps to force the app to quit.

How to force an app to quit

Press these three keys together: Option, Command, and Esc (Escape). Or choose Force Quit from the Apple menu  in the upper-left corner of your screen. (This is similar to pressing Control-Alt-Delete on a PC.)

Then select the app in the Force Quit window and click Force Quit.

You can even force the Finder to quit, if it stops responding: Select Finder in the Force Quit window, then click Relaunch.

Open Unsecure App On Macbook

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Open Unsecure App Mac

How to force an app to close on your iPhone, iPad, or iPod touch.