What causes unfortunately the process com.android.phone has stopped

How do I fix unfortunately the process com Android phone has stopped?

Click on Settings to access apps..
Select Apps..
Click on Sim Toolkit..
Click on CLEAR DATA as well as CLEAR CACHE..
Finally, reboot the Android smartphone and then check whether the Unfortunately, the process com. android. phone has stopped error has been resolved..

Why is my phone saying Unfortunately the process com Android Systemui has stopped?

systemui has stopped” error, an error in which the entire User Interface of a device stops responding, sometimes for as long as an hour. This error can be caused by anything from a faulty custom ROM installation to a deleted OS file or a third-party app. In most cases, it is a third-party app.

What does Unfortunately Android has stopped mean?

"Unfortunately, the app has stopped" error is very common in Android devices, and many factors will cause the error, such as apps out dated, the app that keeps crashing is Android System Webview app.