MBP touch bar late 2016 crashes over and over with "MCA Error" "CATERR detected!"

Two brand new 15" MBPs, 2TB SSD, crash repeatedly with this error.

Crashes while trying to back up with many combinations of:

Seagate USB 3 4TB and Time Machine

WD My Passport Ultra 1TB USB 3 and Time Machine or Carbon Copy Cloner

CalDigit 2TB USB3.1/Thunderbolt with Carbon Copy Cloner

Via Apple USBC-USBA adapters, manufacturer provided USB-C to USB-C cables, or brand new Belkin USBC to USBC cable from Apple store.

Probably a dozen crashes now. EXTREMELY UPSET. Need to use these for business use. As of now, cannot back them up reliably. Waited years for new machines and now this.

Time Machine takes around 24 hours to complete initial backup on usb 3, and one took over 5 days and still did not complete encrypting.

Initially suspected externals and cables, but now so many crashes with so many different configs, it must be the Macs.

Tried Safe Boot, resetting SMC and NVRAM. Same results.

Initially set up by USBC-USBC Apple cable from perfectly functioning 2012 MBPs.