[OnePlus 6T  Questions & Answers] Vlodayax:
What about friends, it happens that I wanted to install TWRP to my OP6T, but it did not go well ... I followed the steps and when I gave "Reboot Recovery", I entered the fastboot mode, and it did not happen there, it did not allow me to flash the rom, the stock recovery, or the TWRP, tells me the following ...

This happens when wanting to boot the twrp.img:

PS C:\Users\vhr07\Desktop> fastboot devices

785694ef fastboot

PS C:\Users\vhr07\Desktop> fastboot boot twrp.img

downloading 'boot.img'...

OKAY [ 0.713s]

booting...

FAILED (remote: Failed to load/authenticate boot image: Load Error)

finished. total time: 0.746s

PS C:\Users\vhr07\Desktop>

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This happens when you want to install the recovery stock:

PS C:\Users\vhr07\Desktop> fastboot flash recovery recovery.img

target reported max download size of 536870912 bytes

sending 'recovery' (65536 KB)...

OKAY [ 1.518s]

writing 'recovery'...

FAILED (remote: (recovery_b) No such partition)

finished. total time: 1.536s

PS C:\Users\vhr07\Desktop>

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I install the recovery by means of "boot" and it says OK, but when wanting to boot I get error:

PS C:\Users\vhr07\Desktop> fastboot flash boot recovery.img

target reported max download size of 536870912 bytes

sending 'boot' (65536 KB)...

OKAY [ 1.518s]

writing 'boot'...

OKAY [ 0.271s]

finished. total time: 1.794s

PS C:\Users\vhr07\Desktop> fastboot boot recovery.img

downloading 'boot.img'...

OKAY [ 1.506s]

booting...

FAILED (remote: Failed to load/authenticate boot image: Load Error)

finished. total time: 1.547s

PS C:\Users\vhr07\Desktop>

---------------------------------------------------------------------------------------------

These were my last attempts ...:

PS C:\Users\vhr07\Desktop> fastboot flash recovery twrp.img

target reported max download size of 536870912 bytes

sending 'recovery' (30948 KB)...

OKAY [ 0.719s]

writing 'recovery'...

FAILED (remote: (recovery_b) No such partition)

finished. total time: 0.734s

PS C:\Users\vhr07\Desktop> fastboot flash recovery recovery.img

target reported max download size of 536870912 bytes

sending 'recovery' (65536 KB)...

OKAY [ 1.508s]

writing 'recovery'...

FAILED (remote: (recovery_b) No such partition)

finished. total time: 1.525s

PS C:\Users\vhr07\Desktop> fastboot flash recovery twrp.zip

target reported max download size of 536870912 bytes

sending 'recovery' (16849 KB)...

OKAY [ 0.391s]

writing 'recovery'...

FAILED (remote: (recovery_b) No such partition)

finished. total time: 0.406s

PS C:\Users\vhr07\Desktop> fastboot flash recovery_b recovery.img

target reported max download size of 536870912 bytes

sending 'recovery_b' (65536 KB)...

OKAY [ 1.523s]

writing 'recovery_b'...

FAILED (remote: (recovery_b_b) No such partition)

finished. total time: 1.538s

PS C:\Users\vhr07\Desktop> fastboot flash boot_b recovery.img

target reported max download size of 536870912 bytes

sending 'boot_b' (65536 KB)...

OKAY [ 1.517s]

writing 'boot_b'...

OKAY [ 0.301s]

finished. total time: 1.824s

PS C:\Users\vhr07\Desktop> fastboot boot recovery.img

downloading 'boot.img'...

OKAY [ 1.511s]

booting...

FAILED (remote: Failed to load/authenticate boot image: Load Error)

finished. total time: 1.549s

PS C:\Users\vhr07\Desktop> fastboot flash boot twrp.img

target reported max download size of 536870912 bytes

sending 'boot' (30948 KB)...

OKAY [ 0.714s]

writing 'boot'...

OKAY [ 0.154s]

finished. total time: 0.874s

PS C:\Users\vhr07\Desktop> fastboot flash boot_b twrp.img

target reported max download size of 536870912 bytes

sending 'boot_b' (30948 KB)...

OKAY [ 0.717s]

writing 'boot_b'...

OKAY [ 0.181s]

finished. total time: 0.904s

PS C:\Users\vhr07\Desktop> fastboot boot twrp.img

downloading 'boot.img'...

OKAY [ 0.716s]

booting...

FAILED (remote: Failed to load/authenticate boot image: Load Error)

finished. total time: 0.746s

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Please, I need your help :( I promise not to ROOT again the hahaha team

I would pay if necessary :(

PD: already tried with bootloader unlocked and blocked

UPDATE: MSMTools, stuck on "PARAM PREPROCESSING"

https://imgur.com/qiaF8oh