[Google Pixel 3 XL Questions & Answers] timg11:
I'm trading my Pixel 3 for the Pixel 3 XL.

I received the 3XL and I first want to update to the latest image.

About says Build Number PQ2A.190205.001.

I downloaded "crosshatch-pq3a.190801.002-factory-15db810d.zip", and unzipped to a temporary directory on a Windows 10 system (the same system I successfully performed a factory flash on the Pixel 3, using the same process, in April)

I ran flash-all.bat, and have the following log output:

D:\Download\Hardware\Google\Pixel3XL\Temp\crosshatch-pq3a.190801.002>flash-all.bat
target reported max download size of 268435456 bytes
sending 'bootloader_a' (8493 KB)...
OKAY [ 0.253s]
writing 'bootloader_a'...
(bootloader) Flashing Pack version b1c1-0.1-5578427
(bootloader) Flashing partition table for Lun = 0
(bootloader) Flashing partition table for Lun = 1
(bootloader) Flashing partition table for Lun = 2
(bootloader) Flashing partition table for Lun = 4
(bootloader) Flashing partition table for Lun = 5
(bootloader) Flashing partition msadp_a
(bootloader) Flashing partition xbl_a
(bootloader) Flashing partition xbl_config_a
(bootloader) Flashing partition aop_a
(bootloader) Flashing partition tz_a
(bootloader) Flashing partition hyp_a
(bootloader) Flashing partition abl_a
(bootloader) Flashing partition keymaster_a
(bootloader) Flashing partition cmnlib_a
(bootloader) Flashing partition cmnlib64_a
(bootloader) Flashing partition devcfg_a
(bootloader) Flashing partition qupfw_a
(bootloader) Flashing partition storsec_a
(bootloader) Flashing partition logfs
OKAY [ 0.591s]
finished. total time: 0.850s
rebooting into bootloader...
OKAY [ 0.070s]
finished. total time: 0.074s
target reported max download size of 268435456 bytes
sending 'radio_a' (71132 KB)...
OKAY [ 1.657s]
writing 'radio_a'...
(bootloader) Flashing Pack version SSD:g845-00017-190312-B-5369743
(bootloader) Flashing partition modem_a
OKAY [ 0.282s]
finished. total time: 1.945s
rebooting into bootloader...
OKAY [ 0.070s]
finished. total time: 0.074s
target reported max download size of 268435456 bytes
archive does not contain 'boot.sig'
archive does not contain 'boot_other.img'
archive does not contain 'recovery.img'
archive does not contain 'system.sig'
archive does not contain 'system.sig'
archive does not contain 'vendor.sig'
archive does not contain 'vendor_other.img'
wiping userdata...
Erase successful, but not automatically formatting.
File system type raw not supported.
--------------------------------------------
Bootloader Version...: b1c1-0.1-5578427
Baseband Version.....: g845-00017-190312-B-5369743
Serial Number........: 8A******C1
--------------------------------------------
checking product...
OKAY [ 0.061s]
checking partition-exists...
FAILED (remote: variable not found)
finished. total time: 0.365s
Press any key to exit...

After this process the phone boots to the factor reset startup process. It is still at Build Number PQ2A.190205.001.

In the log (above), there are multiple messages of the form "archive does not contain '*.img'"

At the end "FAILED (remote: variable not found)"

Any guidance on what went wrong?

I can verify that in the Temp folder I extracted the downloaded ZIP file to, there is another ZIP. image-crosshatch-pq3a.190801.002.zip. That ZIP passes an integrity check. Inside that ZIP there are 20 files (.img and other)