Unable to flash factory ROM on Pixel

I'm trying to restore the factory ROM on my Pixel. I've downloaded and unpacked a [factory image](https://developers.google.com/android/images) for my phone, and when I run sudo ./flash-all.sh I get FAILED (remote: partition [bootb] doesn't exist). Here's the whole transcript. Can anyone suggest a workaround? target reported max download size of 536870912 bytes sending 'bootloaderb' (32728 KB)... OKAY [ 0.836s] writing 'bootloaderb'... (bootloader) Valid bootloader version. OKAY [ 1.600s] finished. total time: 2.435s rebooting into bootloader... OKAY [ 8.593s] finished. total time: 8.693s target reported max download size of 536870912 bytes sending 'radiob' (57192 KB)... OKAY [ 1.428s] writing 'radiob'... OKAY [ 0.909s] finished. total time: 2.337s rebooting into bootloader... OKAY [ 0.006s] finished. total time: 0.106s target reported max download size of 536870912 bytes archive does not contain 'boot.sig' archive does not contain 'recovery.img' archive does not contain 'system.sig' archive does not contain 'vendor.sig' wiping userdata... Creating filesystem with parameters: Size: 122633060352 Block size: 4096 Blocks per group: 32768 Inodes per group: 8192 Inode size: 256 Journal blocks: 32768 Label: Blocks: 29939712 Block groups: 914 Reserved block group size: 1024 Created filesystem with 11/7487488 inodes and 518062/29939712 blocks -------------------------------------------- Bootloader Version...: 8996-012001-1610061102 Baseband Version.....: 8996-012511-1611190200 Serial Number........: XXXXXXXXXXXX -------------------------------------------- checking product... OKAY [ 0.050s] checking version-bootloader... OKAY [ 0.051s] checking version-baseband... OKAY [ 0.050s] sending 'bootb' (24821 KB)... OKAY [ 0.642s] writing 'bootb'... (bootloader) Flashing active slot "_b" FAILED (remote: partition [bootb] doesn't exist) finished. total time: 1.095s