If you're coming from AOSP or A stock MIUI rom or any encrypted rom:

1- wipe dalvik/art cache, data, metadata & cache
2 - flash the rom
3- format data
4- switch active slot to A
5- reboot
If you're coming from other HyperOS port or a decrypted rom:

1- wipe dalvik/art cache, data, metadata & cache
2- flash the rom
3- reboot system
If you're coming from my previous build:

1-flash the rom
2-reboot

0.Flash WhatsApp Working Aosp-miui rom
1.First install WhatsApp another WhatsApp working rom
2.Install Data Backup this app
3. Flash My ROM
4. Restore WhatsApp..
5. Reboot
6. Done

Credits:
PaperOS team(icluded rom) && Kashi for Launcher && xiaomi.eu
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Test Version
First paperos port in fog
Fixed dpi issues
Fixed bootanimation
Fixed many more bugs
I'm lazy say to...