1. is also the most common reason: the "unknown source" option is not checked in the phone settings. Because of security issues, most mobile phone manufacturers are not allowed to install applications from unknown sources by default when they leave the factory. In this case, we just need to check it, but only if your phone has an antivirus application installed. The specific operation is as follows: Open Settings-More-Security-Unknown Source, and then check in the front. This method can solve most problems.
2. The downloaded application format is incorrect. At present, most application formats of Android machines support APK format, but some children's shoes are inadvertently downloaded to JAR format (this format requires a JAVA emulator to be installed normally) or directly downloaded to Apple's IPA format, which naturally cannot be installed. So read the format carefully before downloading.
3. The downloaded application is only suitable for the higher version of Android system, but the current mobile phone system is too low. This situation is also very common. Some children bought their mobile phones a long time ago, but sometimes they want to download the latest applications, and the result is tragic. To solve this problem, we can only upgrade our mobile phone system, there is no other way. Confirm whether it is suitable for the current system version before installation.
4. The mobile phone is out of memory. Mobile phone storage space is limited, but there are many children's shoes that love to play with applications. When they see the applications they are interested in, they want to download them, and they are often reluctant to delete the previous applications. As a result, one day, the space of the mobile phone is running out, and no applications can be installed. The specific way to check the storage space for receiving mail is as follows: Open and set more storage, from which you can clearly see the usage of mobile phone memory and SD card. If there is not much space left, delete some software or files as soon as possible.
5. You can't install any application with screensaver and eye protection software. Many people have the habit of playing mobile phone in bed at night, but the screen of mobile phone is too bright, which will hurt their eyes, so downloading various eye protection applications can make the light of mobile phone dim and soft. In this case, it is definitely impossible to install the application, as shown below. When the eye protection application is open, no application can be installed. Click Close.
6. The application is incompatible, so you can download the application from different platforms.