[Xiaomi Mi 8 Questions & Answers] tsongming:
For the people messaging me,

Sorry for the delay, I have been out of town and have not had time to check XDA for a couple of days. I want to make clear that everything I know about this persist issue is on this thread.

So please do not PM me about this issue, all persist questions must be resolved within this thread, this way when people have success others can benefit. So I will not setup a remote connection to help follow these steps unless you are paying for my time and mostly because a clear solution for all doesn't exist, so it would not be fair to charge you and I would not even accept it because there is no clear fix, and I would not feel right. If I had a clear way to fix every persist issue, I would bend over backwards to help as many as I could.

The big issue with persist is that these steps definitely work for some. but not everyone. Also, there is a lot of bad information out there. such as people sharing their personal persist backup. To be clear if you flash someone else persist backup, it will permanently damage your phones ability to read its own serial number, IMEI and Mac Address, and there is no way to legitimately repair it. However it could be spoofed, but that is just a temporary solution and it will absolutely break again.

For some, the steps outlined here will work. Unfortunately, there is still a lot of people who have been unable to resolve the issue and I can't do anything to help those people.

I used to think that TWRP caused the persist bug. At this point, I am now thinking that this issue is caused by Magisk Canary or maybe Magisk in general?

I say this because today I was prompted for a Magisk update and immediately after installing the new Magisk made by John Wu's new successor, I immediately had the dreaded hard persist failure. Fortunately, I made a TWRP backup of my persist back in August and was able to fully restore my phone...again. But this time it took over 2 hours because my entire phone became encrypted and I had to start clean. I don't think Magisk is unsafe, but I am thinking that it is safer to update Magisk from recovery only. ( I could be wrong, this is just speculation)

Prior to August, I did not have a persist partition backup, I only had the modems, EFS, etc backed up and that was not good enough to fix, I was finally able to restore the phone by following the options that I listed on the OP. Immediately afterwards I made the persist backup. Since then I have had a persist failure about 5 or 6 times. Today was the first time in months.

Unfortunately, it doesn't seem that anyone on any phone knows what causes these persist issues. No one has a clear answer if you have this issue, and these steps do not work, then keep an eye on the persist thread, I will keep it updated with anything that I find regarding fixing these persist issues.

As I have told people privately

The only option for the difficult cases it seems is to hack your IMEI number and that is technically illegal, If I make a post about those steps it will be taken down, and it's just a temporary fix, and it will break again. For this method, you need to find a donor QCN file.

[MENTION=10445939]Leoleo96[/MENTION], [MENTION=5408699]sk3lt[/MENTION]

Finally, I made a flashable zip file, to push persist image to the persist image for rooted roms. If anyone has a phone that is unfixable and they are willing to test the file, i will share it with you. At your own risk. ( It may not even flash, but it may be worth trying)

One last thing, if you live near a official service location , I would suspect that an authorised shop would be able to restore the persist image linking with the correct hex keys.