Hi Community!
I'm sure you've already encountered this: the application suddenly starts to crash. Unable to connect to the network. The phone does not respond or is slowed down. What now?
Unstable applications
If we are the victim of a similar situation, is if very likely because after an update the new version of the application is not able to work properly with the old data.The solution is either to uninstall and reinstall the application or to delete its data (if it is an application that we cannot or do not want to uninstall - for example, a system application or an application installed from an APK file).
Settings, Apps 
Show system apps 
DetailsGo to Settings -> Applications and select Show system applications in the 3point menu. We will find the failing application and display its details. For example, I chose the OneUI Home environment.
In the storage item we see that the application has some data stored. Click on Storage and we will see the following screen:
Data and cache
Here are two important sections: cache and data. Cache is a temporary application data and a relatively common source of trouble. They can be safely deleted, each application should expect to lose this information and simply recreate it.
In the storage item we see that the application has some data stored. Click on Storage and we will see the following screen:
Data and cacheHere are two important sections: cache and data. Cache is a temporary application data and a relatively common source of trouble. They can be safely deleted, each application should expect to lose this information and simply recreate it.
You may be wondering why there is such a thing when there are problems with it? It's simple, it's information that is often used, but it takes time to get it, so the application stores it in a faster storage. In the case of a web browser, these can be images; Netflix stores downloaded videos here, and Spotify stores songs. Nothing that would be irreplaceable, but still, why download it over and over again from the network, when I can save it locally?
The problem can arise, for example, when something on the server changes, but the application has stored old data, which the server rejects and the application does not count on such a possibility and crashes. Then deleting this data will help.
So press the Clear cache icon. The screen flashes quickly and nothing happens at first glance. It doesn't matter, we'll quit the application if it's running and run it again to see if clearing cache helped.
If not, we'll focus on the second item, data. Here we are already in dangerous area, because these are the configuration data of the application. This can be the account under which you log in by e-mail or in general to any application. These can be stored passwords. In the case of games that do not use Google Play to save the position, there are all your results achieved (eg Flappy Bird stores your highest score here!). Deleting this section is actually the same as reinstalling the application. The next time you run the application, it will look as if it was newly installed.
If not, we'll focus on the second item, data. Here we are already in dangerous area, because these are the configuration data of the application. This can be the account under which you log in by e-mail or in general to any application. These can be stored passwords. In the case of games that do not use Google Play to save the position, there are all your results achieved (eg Flappy Bird stores your highest score here!). Deleting this section is actually the same as reinstalling the application. The next time you run the application, it will look as if it was newly installed.
Unstable system
Sometimes it happens that not only one application is unstable, but more of them crash. In this case, it is possible to clear the system cache. To do this, we need go into recovery. The procedure may differ from phone to phone, but the first step is always to turn off the device completely. Then, usually press the volume up button and the power key and hold until the logo appears. The phone then starts recovery instead of a normal start. In it, the menu items are switched with the volume buttons and the selection is confirmed with the switch.
Example for Galaxy Note 10:
Sometimes it happens that not only one application is unstable, but more of them crash. In this case, it is possible to clear the system cache. To do this, we need go into recovery. The procedure may differ from phone to phone, but the first step is always to turn off the device completely. Then, usually press the volume up button and the power key and hold until the logo appears. The phone then starts recovery instead of a normal start. In it, the menu items are switched with the volume buttons and the selection is confirmed with the switch.
Example for Galaxy Note 10:
Confirm, select Reboot and wait for the phone to boot up. The first start can take significantly longer, the system creates deleted data again, wait patiently.
When it's really bad
It may not be enough to clear the cache. In this case, you only have to reset the phone.
Settings, General management 
Reset 
Factory data resetGo to the Settings -> General management -> Reset and choose Factory data reset.
Press the button to continue.
The phone will then ask you for a password.
Then the phone restarts, complete deletion takes place and after a long time the device starts up in the wizard for the first start. It's like unpacking your phone.
When it's the worst
What? Worse than a complete erase? Well, because we need to get on the phone to the previous procedure. But what if the whole environment is so unstable that we can't get into the settings? In that case, we can reset the phone to factory settings.
We proceed in the same way when deleting the cache partition, but instead of the Wipe cache partition, select Wipe data / factory reset. As you can see, a red warning is displayed. If you confirm the selection, the phone will be completely restored and then the first start-up wizard will start.
You may have wondered: what's the difference between doing a factory reset from the setup menu and from recovery? The difference is that when we go through the phone menu, we enter the password and the phone notes that the deletion was correct. If we go through recovery, no password is entered and the phone will want it for you during the startup wizard.
Be very careful about this, and if you are selling your phone, always perform a renewal from the phone menu. If, on the other hand, you buy a second-hand phone, go through the guide and make sure that you do not encounter a barrier in the form of a request to enter a previous account and password, it could be hard to find.
And yes, now is a good time to make sure you know the accounts to which the phone is logged in and the relevant passwords. You will definitely need a Google Account and you should also be signed in to your Samsung account. Don't be ashamed to write down your account and password, ideally on paper.
In conclusion
Of course, I wish you never needed this article. But if you do, perhaps it will save you a moment of searching and even visiting a service.
