Hello,
There are several possible reason's why you're encountering this issue. Before trying to perform a factory reset, let us try the following steps again:
- Make sure that you have a stable Wi-Fi internet connection.
- Check if Time and date settings are correct.
- Cancel all the pending downloads.
- Perform a soft reset. Press and hold Volume down and Power buttons until the phone vibrates and restart.
- Try downloading or updating apps again.
If the issue still persists, you may need to perform a factory reset. This method usually rules out some software issues. Since this will remove all your apps, photos, messages, and other files, it is best that you create a backup to avoid data loss. You can restore from a backup during the initial set up which will bring your files and settings back.
To reset your phone, go to Settings > About > Reset your phone.
Don't hesitate to ask the community if you need more help.