[Huawei P20 Pro Guides, News, & Discussion] sarichter:
This was done on the Huawei P20 Pro L29C636 variant.

My phone does have it's bootloader unlocked and has been previously rooted.

As stated on just about every other thread, I do not take responsibility for anything that happens to your phone. The method described below is what I experienced with my phone, with the various modifications I had made in the past, and using software other people have developed.

You assume all risk to your equipment.

OTA updates stopped on EMUI 8.0 so I had to find a solution to get the latest EMUI and security patches. Below is the list of software and instructions that I followed to complete these incremental updates. If you own a different regional variant (i.e. L29C432), you can still follow the same instructions, but pay attention to your build numbers when trying to upgrade past 8.1. When jumping from 8.1 to 9.0 and 9.0 to 9.1 you MUST upgrade to the firmware approved for your particular phone variant prior to the new EMUI update. There is a chance you will soft brick your phone, but as long as fastboot still works, you can recover.

Step 1:

Download these two files.

HiSuite_9.0.2.304.zip

hisuite.zip

Install the HiSuite application, do not upgrade the application, and close the program.

Copy the httpcomponent.dll file to C:\Program Files (x86)\HiSuite

Copy the HiSuiteConfig.xml to C:\Users\*username here*\AppData\Local\HiSuite\UserData\UpdateDogDev

Step 2:

Open your system host file at C:\Windows\System32\drivers\etc\hosts

Add these lines to the bottom of the file:

188.225.84.142 query.hicloud.com

Save the file... be sure it saves over the current file and not a new file with a file extension.

Step 3:

Open your Network Connections window in Control Panel here:

View attachment 5146573

Right click on your active Network Connection and go to Properties.

In the dialog box, click on Internet Protocol Version 4 and click the Properties button below the box.

In the dialog box, change your DNS Preferred to 188.225.84.142 and DNS Alternate to 1.2.3.4.

Click the box for Validate Settings Upon Exit just to make sure you do not have any network errors.

Step 4:

Download and open Firmware Finder on your phone here Firmware Finder

Open the program, check the top button is the model variant of your phone, and click the top button.

View attachment 5146583

The list of firmware shown in this program will work for your phone. To be safe, select the firmware you want to upgrade to, and click Check Firmware Access then Check Availability to confirm it is approved for installation.

View attachment 5146585 View attachment 5146589

After you select the firmware you want to upgrade to, click on eRecovery for all versions and click through each prompt until you reach the prompt to Register Update. Click Register Update and this will register your IP address with this specific firmware. I do not know how long this stays registered for, but it will not expire for the time it takes to download and install the firmware.

View attachment 5146593

Step 5:

Connect your phone to your PC with the proper cable, open HiSuite on your PC, and allow the application to install HiSuite on your phone.

Once HiSuite registers that your phone is connected click the Update button near the bottom of the screen.

A dialog box will pop up and recognize the new firmware you registered with Firmware Finder. Double check that the model and regional variant match your phone just in case you goofed up the selection.

View attachment 5146597

This process does take some time since the firmware files can be upwards of 5GB. Be patient and do not interrupt the process. After it downloads, it will push the files to your phone (HiSuite calls is Installation), and then your phone will restart. After your phone restarts, you will get an EMUI update screen indicating that it is indeed updating your system. Once complete, the phone will restart, and you will have an shiny new upgraded phone.

I have read plenty of responses in other threads describing installation failures, stalled installations, or other negative outcomes. Here are a few tips:

RE: Soft Brick - Remember to factory reset/wipe data in eRecovery. This will not wipe your phone, but it will help you get back to some sort of recovery state whether it's eRecovery, TWRP, or back to the system.

RE: Failed Installations - Remember to check the firmware availability in Firmware Finder on your phone and not on the PC. This will avoid accidentally trying to install firmware meant for another variant.

RE: Stalled Installations - I prefer modifying the DNS settings on the computer that is connected to the phone using HiSuite. This avoids DNS settings that don't stick in router settings or a PC bypassing them altogether.

If you do soft brick, you can always HiSuite to recover and rollback the firmware on your phone. I also do have another technique in case HiSuite cannot recover your phone. Just to be clear that this other technique was only tested on the L29C636 variant, but it most likely will work on other global models.