Why, after building the android studio project into an apk file, does an error occur when launching this file on the phone?

Question

Java

After sending this file to the phone and running it, the error "Installation failed" crashes, how can I fix this? tell me please

Answer 1

If you yourself upload your apk to your phone, then you need to "Settings\u003e Security" in the "Unknown sources" section, enable the "Allow installation of applications from unknown sources" option.
Also, see what messages are displayed on the phone screen during installation, perhaps there the user will still be asked to confirm that the installation can continue.

Answer 2

1) Is developer and debug mode enabled?
2) Whether the option "Unknown sources" is enabled.
When you install an application through the IDE, it installs and launches the application itself. Don't forget to check the connection type as well: File Transfer, MTP etc.
+ during installation of the IDE application, permission may be required

Answer 3

1. Check the card in your phone. My old card sometimes refuses to work.
2. There may be a problem with the apk itself. Try to recreate apk without pro-guard.
3. If you sign, try to sign only V1.