Mac Pro supports up to one or two solid-state drive (SSD) modules, depending on the capacity. The SSD modules are paired to and encrypted by the T2 Security Chip. If you replace the SSD modules, use Apple Configurator to erase and set them up for your Mac Pro.
To install or replace the SSD modules in your Mac Pro, here's what you need:
Uninstall and install SSD modules
Do not proceed unless all data from the existing SSD has been backed up. Once a new SSD pairing operation has started, the data on the existing SSD is not recoverable.
Restore the firmware
After you install the new SSD modules, restore the firmware on the Apple T2 Security Chip and erase the internal flash storage on your Mac.
Learn how to install and replace parts in your Mac Pro (2019).