Meaning
The installed package is signed with a different key, so Android blocks the update.
Causes
- App was previously installed from a different source
- Signing key changed between builds
- Trying to install a debug build over a release build
Fixes
- Uninstall the existing app and reinstall
- Use the same signing key as the installed app
- Install the correct build variant
Example
INSTALL_FAILED_UPDATE_INCOMPATIBLE
FAQ
- Will uninstalling fix it?
Yes, but it removes app data unless backed up. - Is this a signing key issue?
Almost always. Use the same signing key.
Contact
If this is a managed app, contact your MDM admin.