If your PS4 is crashing on you, experiencing all sorts of glitches, freezes, save errors, connectivity issues, and so on, a factory reset can restore the device to proper working order.
Factory resetting a PlayStation 4 will erase all of the data on the console, from save info to images and videos and more, so make sure you back up your console before doing a reset.
And if you're selling, trading, or giving away your PS4, you should do a factory reset precisely because it erases all of your personal information.
Either way, before doing the reset, make sure you deactivate the console as your primary unit, or you might later have issues accessing online content or re-loading your data onto a new or refreshed device.
You can deactivate the PS4 through the "PlayStation Network/Account Management" tab in the Settings menu. Hit the "Activate as Your Primary PS4" tab, and then select "Deactivate."
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How to factory reset a PS4
1. In the Settings menu, go to the "Initialization" tab. (You may have to sign in to your user account after the deactivation step above.)
2. Select "Initialize PS4."
3. On the next page, choose "Full."
Your PlayStation 4 will now begin to wipe itself clean, restoring the hardware to its never-used, fresh-from-the-factory settings. The process may take more than an hour.