If you are using a Huawei phone and the application cannot be installed or the installation fails, you can do the following:

1. Check whether the storage space is sufficient. Please go to Settings > Storage to check whether the remaining internal storage space is greater than the memory required to download the application. If it prompts that the storage memory is insufficient during the installation process, you can try to clean the application, release the storage memory required to download the application and reinstall it.

2. Turn on the switch for downloading applications from unknown sources. If the application is not downloaded from the application market (such as QQ Browser, Baidu, Chrome browser), please perform the following operations:

EMUI 8.X previous versions: Enter settings, search for unknown source application downloads, Turn on this switch.

EMUI 9.X & EMUI 10.X & EMUI 11.X & Magic UI 2.X /3.X/4.0: Enter settings, search for external source application downloads, turn on this switch, and install at the same time Within the external source app, find the corresponding browser and turn on the switch to install other apps within the app.

3. Restart the phone. Switching to other interfaces during the installation process of apps downloaded from non-app stores will cause the installation to stop. It is recommended to restart the phone to release the occupied space and try to avoid exiting the installation interface midway.

4. Device Manager closes the activated application. If it prompts "Security policy prohibits the installation of applications from this installation source", please open settings, search and enter the device manager, and close the activated application.

5. Download the installation package from official channels. If you receive a pop-up message such as "Installation parsing failed, no signature, abnormal signature, inconsistent signature, trying to modify system files" during the installation process, it is recommended to obtain a reliable installation package from official channels.

6. Check whether third-party housekeeping software is installed. Please check whether third-party housekeeping software (such as 360/Tencent Housekeeper, etc.) is installed. If so, you can try to uninstall the software and try again to avoid conflicts caused by multiple housekeeping applications running at the same time.

7. Delete the "App Market" data. If the App Market cannot be installed after downloading, it is recommended to delete the data in the App Market and try to reinstall it. The operation path is: enter Settings, search for App Management, find the App Market, and click Storage > Delete Data.

If the above method fails to solve the problem, please back up the data in advance (WeChat/QQ and other applications need to be backed up separately), and bring the purchase voucher to the Huawei Customer Service Center for inspection and processing.