Greetings ,
This is a very sensible question I wish more people would ask.
In some situations an error 70 can be a problem reading stored images on a memory card.
https://support.usa.canon.com/kb/index?page=content&id=ART177668
In other situations, it can indicate a more serious problem. I would not rely on a firmware update to resolve an error 70 condition. You'd be better off resetting the camera to defaults. I would also try a different battery and new or freshly formatted memory card. An error 70 is usually a software issue, but the underlying cause can be hardware related. If the above suggestions don't help, the camera should be inspected by Canon.
Depending on the serial number, some 70Ds were prone to this error.
https://www.usa.canon.com/support/canon-product-advisories/service-notice-eos-70d-error-70-or-error-...
Canon stopped repairing the PCB for free in December of 2022.
~Rick
Bay Area - CA
~R5 C (1.0.7.1) ~RF Trinity, ~RF 100 Macro, ~RF 100~400, ~RF 100~500, +RF 1.4x TC, +Canon Control Ring, BG-R10, 430EX III-RT ~DxO PhotoLab Elite ~DaVinci Resolve ~Windows11 Pro ~ImageClass MF644Cdw/MF656Cdw ~Pixel 8
~CarePaks Are Worth It
