Installs keep failing on Xiaomi, Redmi or POCO
MIUI and HyperOS ship a setting called MIUI optimization that blocks third-party installs, usually without explaining why.
Why it happens
MIUI optimization changes how the system handles package installation, among many other things. When it interferes, the failure surfaces as a generic error with no mention of the setting, so there is nothing in the message to search for.
How to fix it
1. Turn off MIUI optimization, install, turn it back on
It lives in Settings → Additional settings → Developer options. You need Developer options unlocked first (tap the MIUI version number several times).
2. Expect the interface to look wrong while it is off
With the setting disabled, system theming renders differently and parts of the UI can look broken. Restarting the phone restores it. This is a side effect of the workaround, not damage.
3. Check Install via USB and unknown sources too
MIUI has additional per-source install permissions that other Android versions do not, and they are easy to miss.
Also shown as
- MIUI optimization install failed
- HyperOS cannot install apps
- Xiaomi install blocked