1st time Flashing SHRP ON 1st Time bootloader unlocked users or users on fastboot rom with mi recovery :-

•Encryption

1) Go to Recovery && Click on wipe && Format data by typing yes
2) Reboot recovery again
3) Wipe system, vendor ,data , dalvik ,cache

4) Copy rom files to ur internal or external storage
5) Flash firmware (not necessary in miui )
               Rom
               Gapps   (needed only in some roms)
6) Go back to tweaks & Apply Stock Recovery Deactivation

7) Reboot to system

1) Go to wipe section & Click on Advanced Wipe
2) Wipe system,data,vendor, dalvik ,cache

3) Flash firmware (not necessary in miui )
               Rom
               Gapps   (needed only in some roms)
4) Just Go back to tweaks in Recovery
5)Apply these two tweaks
----> Stock Recovery Deactivation
----> Disable Force encryption-v3

6) Reboot to system
Notes:- 1) No need of Stock Recovery Deactivation on other aosp roms

2) Whenever u go from encryption to decryption and vice-versa ckean flash with format data is must