[Xiaomi Mi A2 / 6X Guides, News, & Discussion] firdausimbolon:
Hi, everyone. Maybe here's some people that have problem with their Mi A2/Mi 6X when flashing ROM and get Error 28 in TWRP no matter what version. Recently I got this error when flashing.

It give pain on my head since I'm sure the ROM isn't broken, even I tried to test it and redownload it but still get same Error. But, today I can flash my phone with no problem and 'Error 28'. Then let me write what's I do before I can fix it and what's the culprit that makes this problem. In this case I'll use ViperOS ZIP that I downloaded recently since latest ZIP that I downloaded is broken (it's perfect so I can tell you the problem more detail)

0. Make sure if your ZIP File of Flashable ROM isn't damaged (corrupted, tampered, etc.) with checking it use WinRAR/7Zip in-built tester (in this case, I use WinRAR in-built test since it have similar feature with other zip tester).

1.A. IF it ended with line 'No errors found during test operation', then you can go to step 2

on PC, or

on your Phones

1.B. BUT IF it ended with showing WinRAR diagnostic message on title like this

in your PC, or

in your Phone

then you need to redownload it again

1.C. Additional :

It very recommended to test checksum if you're not sure about the test above or you're not sure about your ZIP integrity. You can use any checksum tester that you can search in google, in this case I'll use "HashTab" from Implbits since it simpler. I'll check the MD5 checksum here since it faster (maybe. you can try SHA1 too if you curious)

You need to check the ZIP checksum that you downloaded in ROM's website (Sourceforge, etc.) like this

Then you can use Checksum software to match it checksum from website and file that you downloaded. If your ZIP have same checksum like this (matching checksum with last image above)

Then you can go to next step, but if it not same like this

Then you need to redownload it again from source.

2.A. If you're already have good ROM's Flashable ZIP that in your Mi A2/Mi 6X (I'll assume your phone have OS and usable) then you can flash it from TWRP and will not face 'Error 28' again (and you can ended this tutorial here since your problem was fixed). BUT ...

2.B. If you download it from your PC/Laptop/Other devices that need USB cable to transfering to your Mi A2/Mi 6X, then you aware about two things:

- USB Cable

- USB Port from PC/Laptop/Other Devices

In My case, my USB Cable is the culprit of my problem that always give me 'Error 28'. Changing with other USB Cable fix my problem (I was test the ROM again with WinRAR in-built tester and it can flashed properly), it have 99% chances to give error. 1% other is your USB Port in your PC/Laptop/Other Devices since.

3. What if you get that ROM from other devices using app like ShareIT, MiDrop, Bluetooth, etc.? Then you need to check it integrity again use checksum tool/WinRAR in-built tool to verify if it ZIP is OK like in step 1.

That's all that I know to solve Error 28 in my Mi A2/Mi 6X. Hope it will fix your problem too and sorry if I can't good thread and have bad english. If you have any question or something else that you know, please comment below. Thank you.