[Google Pixel 2 XL Questions & Answers] chimeracoder:
I'm trying to root my phone, but I can't flash any boot or recovery images to it, whether that's the patched boot.img, TWRP, or even the stock factory images themselves. I've already unlocked the bootloader, using

fastboot flashing unlock_critical

.

I am running the newest version of adb and fastboot, downloaded yesterday:

$ fastboot --version
fastboot version 0.0.1-4500957
Installed as [REDACTED]

$ adb version
Android Debug Bridge version 1.0.39
Version 0.0.1-4500957
Installed as [REDACTED]

When I try to flash the stock factory images, downloaded straight from Google, I get this series of errors:

$ adb reboot bootloader
$ ./flash-all.sh
target didn't report max-download-size
sending 'bootloader' (36344 KB)...
FAILED (remote: Requested download size is more than max allowed
)
finished. total time: 0.000s
rebooting into bootloader...
OKAY [ 0.000s]
finished. total time: 0.201s
target didn't report max-download-size
sending 'radio' (60428 KB)...
FAILED (remote: Requested download size is more than max allowed
)
finished. total time: 0.000s
rebooting into bootloader...
OKAY [ 0.001s]
finished. total time: 0.201s
extracting android-info.txt (0 MB) to RAM...
Warning: Could not determine slot for secondary images. Ignoring.
extracting boot.img (40 MB) to disk... took 0.289s
target didn't report max-download-size
archive does not contain 'boot.sig'
extracting dtbo.img (8 MB) to disk... took 0.039s
archive does not contain 'dtbo.sig'
archive does not contain 'dt.img'
archive does not contain 'recovery.img'
extracting system.img (1936 MB) to disk...
archive does not contain 'system.sig'
extracting vbmeta.img (0 MB) to disk... took 0.000s
archive does not contain 'vbmeta.sig'
extracting vendor.img (349 MB) to disk... took 4.445s
error: Failed to identify current slot

Other fastboot commands also fail with inconsistent error messages and failure modes:

$ fastboot flash boot boot.img
target didn't report max-download-size
sending 'boot' (40960 KB)...
FAILED (remote: Requested download size is more than max allowed
)
finished. total time: 0.000s

If I try with the -S flag:

$ fastboot -S 512K flash boot boot.img
Invalid sparse file format at header magic
sending sparse 'boot' 1/51 (508 KB)...

which hangs indefinitely, never sending even the first segment.

I can try booting directly, which yields the same problem:

$ fastboot boot boot.img
downloading 'boot.img'...
# hangs indefinitely

Similarly,

$ fastboot --set-active=_a

hangs indefinitely as well. I have to restart the bootloader to kill it, at which point it just prints the confusing error:

Device does not support slots

(the Pixel 2 XL does support slots!).

The error messages aren't always consistent; sometimes the first fastboot flash boot boot.img command will appear to hang (requiring a restart, similar to

--set-active

) instead of printing the error message about max-download-size. I've let that run for about fifteen minutes before having to kill it. Unlike system.img, boot.img is only about 40MB, so it shouldn't take that long to flash - something is clearly wrong.

I've also tried this with multiple cables on different USB ports, with the same sorts of results each time.

Am I missing a step? How can I flash the factory images and the patched boot.img?