How to solve Android 7.1 flash failure with remote data too large? It started when the regular OTA update failed to install and left me with a "no command" screen. 
I downloaded a stock ROM from the official developers.google site.
I tried the flash-all script to install the ROM. It gave me the following:

archive does not contain 'boot.sig'
archive does not contain 'recovery.sig'
failed to allocate -1492308812 bytes
error: update package missing system.img


After pasting all the files from the image.zip to the parent folder with the flash-all script in it (that way the system.img is in the same dir as the flash-all script), I received the same error.

After some googling I found some instructions to flash the files manually using fastboot.
All went well and I came to the second last instruction to flash the system.
Then this happend:

&gt;&gt; fastboot flash system system.img
target reported max download size of 536870912 bytes
erasing 'system'...
OKAY [  0.090s]
sending sparse 'system' (520374 KB)...
OKAY [ 20.706s]
writing 'system'...
OKAY [  9.350s]
sending sparse 'system' (515510 KB)...
OKAY [ 22.374s]
writing 'system'...
OKAY [  9.586s]
sending sparse 'system' (479538 KB)...
OKAY [ 20.531s]
writing 'system'...
OKAY [  8.527s]
sending sparse 'system' (514677 KB)...
OKAY [ 21.401s]
writing 'system'...
OKAY [ 11.339s]
sending sparse 'system' (524289 KB)...
FAILED (remote: data too large)
finished. total time: 124.427s


As you can see, fastboot is already sending the data in smaller portions. What do I have to do to fix this?
I searched google but couldn't find any usable fix..


The phone is an rooted Nexus 5x.
Turns out that some old adb tooling was in my PATH variable, so I was using an old version of fastboot.. 
It all worked well when I used the right version!

Will accept this as an answer in 2 days.