Hi, Mi Fans,

The craze for Android 10 is increasing day by day and every Custom ROM developers are working hard to create Android 10 Custom ROMs more reliable. Recently I have posted a review of Pixel Experience ROM based on Android 10 for Redmi Note 7 Pro. As it's Android Security Patch level was of 5 November 2019, the ROM's flashing method was the same as the older flashing method. But ROM's having Android Security Patch level after 5 December 2019 have quite a different flashing method and if you have followed the older method you probably have seen an error.
So, in this thread, you will get to know how to rid off from this error.

To flash the Custom ROM successfully, you have to flash the beta firmware of the device before flashing the Custom ROM.
To flash these files, I will suggest you use Orange Fox recovery.

Oragefox Recovery: Click here
Latest Xiaomi beta firmware: Click here

To know how to install Custom Recovery, go to the following thread: How to Install Custom Recovery?

The steps of flashing files are the same as mentioned in the following thread: How to Install Flashable Files using Custom Recovery?
But, you have to flash the Device's beta firmware first then flash the Custom ROM.