[OnePlus 6T  Guides, News, & Discussion] mxz55:
* Pre-note: Extracting firmwares and subsequently updating your phone's firmware by flashing the extracted firmwares, is a 2-part process. This guide is only about extracting them, and i also made another guide that is for flashing them afterwards: see [GUIDE] Flashing the latest firmware updates to your OnePlus 6T. The guides supplement eachother, depending on your needs.

General word about firmware updates:

A lot of people know of the importance and benefits of keeping your device firmware updated, just like you keep your custom ROM updated. If you don't keep them updated, you might not get the best out of your custom ROM (like: more bugs, system stability and performance problems/less speed.. also, vendor components, e.g Qualcomm and other chips, have security patches in the firmware.. "Vendor patch level" vs Android "Security patch level").

Besides incremental firmware updates from each OxygenOS release with a small changelog, too many people are missing out on huge jumps such as that they are running an Android 11 custom ROM, while their firmware was never updated so it remained a firmware originally shipped with an Android 10 (or earlier) OxygenOS release. Staying behind on huge jumps like these, cause the biggest list of problems with stability and performance. Therefore it is advisable to keep your firmware updated, and note that even small incremental updates (based on the same Android version) tend to give performance, security and stability benefits.

Let's continue.

If you can't find someone that posted the firmwares separately (or you don't trust their completeness, integrity & authencity.. it's always a potential risk) this guide will help you do it all by yourself, to extract firmwares from the original ROM update package.

GUIDE STARTS BELOW THIS LINE

Prerequisites

First step: Get the updated OxygenOS ROM, it's a zip file named in a format like this: OnePlus6TOxygen_34.J.62_OTA_0620_all_2111252336_339a2fa8335f21.zip (this happens to be the latest version as of writing, it will be outdated from now on)

Make sure to get it from an official source, i dont know where OnePlus shares direct links but i know that their practises regarding it are inconsistent (sometimes they provide, other times they don't). So i advise you to use an useful app in the Play store called Oxygen Updater that fetches it directly from OnePlus servers.

For this app.. if you're on LineageOS, you can click through to download the ROM update file but only after ignoring all warning dialogs saying things like "Unsupported device" and about root + enabling Advanced mode slider in the app's settings. So basically, these steps override 1) that you're on LineageOS (so it thinks it's unsupported) and 2) that it doesn't recognize your current version and thus doesn't offer a direct download of the file, regardless of what it fails to detect about your phone or OS, to your phone storage.. that's what Advanced mode takes care of. So after enabling Advanced mode, download the ROM .zip from the update screen in the app, and it will be placed in your phone's storage root folder

So now that you have the ROM, let's start the firmware extracting process -

Required tool: payload-dumper-go > choose latest version and download the Windows package

1) Extract payload-dumper-go to your folder "FW update"

2) Move the ROM .zip file (downloaded from Oxygen Updater app) from your phone storage to your PC, and place it in that "FW update" folder

3) Open the ROM .zip file with an archiving program, like 7-Zip

4) Extract payload.bin from within the ROM .zip file using 7-Zip, this .bin file should display in 7-Zip as shown below:

So after extracting this from the ROM .zip, you open up cmd (command prompt of Windows) and write cd [folder "FW update" location) or even better, copy cmd.exe from System32 to your "FW update" folder. I always use that method for all my maintenance, e.g it's copied to my "adb" folder as well for easy folder targeting

4) Now in cmd, use payload-dumper-go to pull firmwares from payload.bin:

Enter each command separately, after the other completes

payload-dumper-go -p abl payload.bin
payload-dumper-go -p aop payload.bin
payload-dumper-go -p bluetooth payload.bin
payload-dumper-go -p cmnlib payload.bin
payload-dumper-go -p cmnlib64 payload.bin
payload-dumper-go -p devcfg payload.bin
payload-dumper-go -p dsp payload.bin
payload-dumper-go -p fw_4j1ed payload.bin
payload-dumper-go -p fw_4u1ea payload.bin
payload-dumper-go -p hyp payload.bin
payload-dumper-go -p keymaster payload.bin
payload-dumper-go -p LOGO payload.bin
payload-dumper-go -p modem payload.bin
payload-dumper-go -p oem_stanvbk payload.bin
payload-dumper-go -p qupfw payload.bin
payload-dumper-go -p storsec payload.bin
payload-dumper-go -p tz payload.bin
payload-dumper-go -p vendor payload.bin
payload-dumper-go -p xbl_config payload.bin
payload-dumper-go -p xbl payload.bin

Now they are pulled, but will be automatically put in folder names (as subfolders to your "FW update" folder) that look like this: "extracted_20211216_135146" with unique number each. These folders contain just 1 pulled firmware (.img files) individually

Now you have to move all .img files from each of such folders, to your main directory ("FW update"). I prefer to do it like this: Windows Explorer search for *.img like below image

Select all matching results from this search and copy them to "FW update" or put them in a new subfolder "Pulled firmwares"

Now the firmware extracting process is complete. From this point, the flashing process should be picked up. I made another guide for the flashing process, if you're interested beyond the scope of this one (the act of extracting firmwares alone): [GUIDE] Flashing the latest firmware updates to your OnePlus 6T

Note on this guide: it's possible that these instructions are universal to many, if not all, other modern OnePlus devices.. or even other smartphone brands. But since i am only the owner of an OnePlus 6T, i cannot verify or test it, and therefore this guide targets the 6T. But of course, if you got some know-how you can attempt to use this guide for other models.. although you will surely have to dump the content table listing of the update's payload.bin (with this command: payload-dumper-go -list payload.bin ), to figure out which .img files to extract.. as the relevant firmware packages & components will differ per model