[Xiaomi Redmi 3s Questions & Answers] jirislav:
By running logcat while attempting to re-install the guard app (com.miui.guardprovider), I see the followin error (FYI I see this error when installing any app):

[ 01-21 03:49:18.090 1462: 2549 I/ActivityManager ]
START u0 {dat=file:///storage/emulated/0/Root_Uninstaller_Backup/Bezpečnostní prvky MIUI_null.apk cmp=com.google.android.packageinstaller/com.android.packageinstaller.InstallAppProgress (has extras)} from uid 10023 on display 0

[ 01-21 03:49:18.095 1462: 2549 D/ActivityTrigger ]
ActivityTrigger activityPauseTrigger

[ 01-21 03:49:18.098 3467: 3501 I/Finsky ]
[25] com.google.android.finsky.bo.an.run(6): Stats for Executor: NotificationAssistDatabaseManager com.google.android.finsky.bo.ao@787defb[Running, pool size = 0, active threads = 0, queued tasks = 0, completed tasks = 6]

[ 01-21 03:49:18.106 1462: 2301 I/Timeline ]
Timeline: App_transition_ready time:1710168

[ 01-21 03:49:18.120 11313:11313 W/ResourceType ]
No package identifier when getting name for resource number 0x00000000

[ 01-21 03:49:18.124 1462: 2507 W/ResourceType ]
No package identifier when getting name for resource number 0x00000000

[ 01-21 03:49:18.125 1462: 2507 W/ ]
Unable to open '/storage/emulated/0/Root_Uninstaller_Backup/Bezpečnostní prvky MIUI_null.apk': Permission denied

[ 01-21 03:49:18.125 1462: 2507 W/zipro ]
Error opening archive /storage/emulated/0/Root_Uninstaller_Backup/Bezpečnostní prvky MIUI_null.apk: I/O Error

[ 01-21 03:49:18.125 1462: 2507 D/asset ]
failed to open Zip archive '/storage/emulated/0/Root_Uninstaller_Backup/Bezpečnostní prvky MIUI_null.apk'

[ 01-21 03:49:18.129 2724: 2724 W/ContextImpl ]
Calling a method in the system process without a qualified user: android.app.ContextImpl.sendBroadcast:788 android.content.ContextWrapper.sendBroadcast:411 android.content.ContextWrapper.sendBroadcast:411 com.miui.permcenter.install.PackageVerificationRecevier.ar:-1 com.miui.permcenter.install.PackageVerificationRecevier.onReceive:-1

[ 01-21 03:49:18.135 1462: 2332 W/ActivityManager ]
cann't getContentProviderImpl: guard, cpi is null.

[ 01-21 03:49:18.135 2724: 9453 E/ActivityThread ]
Failed to find provider info for guard

[ 01-21 03:49:18.135 2724: 9453 E/PackageVerifyedRecevier ]
parseApk
java.lang.IllegalArgumentException: Unknown URI content://guard
at android.content.ContentResolver.call(ContentResolver.java:1424)
at com.miui.permcenter.install.q.doInBackground(Unknown Source)
at com.miui.permcenter.install.q.doInBackground(Unknown Source)
at android.os.AsyncTask$2.call(AsyncTask.java:295)
at java.util.concurrent.FutureTask.run(FutureTask.java:237)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1113)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:588)
at java.lang.Thread.run(Thread.java:818)

[ 01-21 03:49:18.135 2724: 9453 D/PackageVerifyedRecevier ]
verify package /storage/emulated/0/Root_Uninstaller_Backup/Bezpečnostní prvky MIUI_null.apk info: null

[ 01-21 03:49:18.135 2724: 9453 D/PackageVerifyedRecevier ]
verify package /storage/emulated/0/Root_Uninstaller_Backup/Bezpečnostní prvky MIUI_null.apk finish false

[ 01-21 03:49:18.136 1462: 2507 I/com.android.server.pm.PackageManagerServiceInjector ]
MIUILOG- INSTALL_FAILED_VERIFICATION_FAILURE uid: 10023 pkg : com.google.android.packageinstaller

[ 01-21 03:49:18.138 9998: 9998 D/PackageVerificationReceiver ]
PackageVerificationReceiver onReceive:Intent { act=com.miui.global.packageinstaller.action.verifypackage flg=0x10 cmp=com.miui.global.packageinstaller/.PackageVerificationReceiver }

Would it be possible to skip resolving the content://guard link? I've already tried to go to Settings -> System apps settings -> Security -> Security scan and unchecked the "Scan before installing" button, but the error is still the same :/

Any ideas how to fix this?

Btw, I've tried to post this to the development section, but I was rejected due to the fresh account, so that's why I'm writing here.