Naming things
Using mboot as a name for the application loader was a bad idea, as this name is already taken within the MicroPython ecosystem.
See also micropython/ports/stm32/mboot/README.md at master · micropython/micropython · GitHub
Welcome, UMAL
So, we just renamed this guy to Universal MicroPython Application Loader (umal) per Improve multi-platform support · hiveeyes/terkin-datalogger@21314d9 · GitHub and mitigated all references to the former name throughout the codebase and the forum.
>>>
PYB: soft reboot
[boot.py] INFO: Python module search path is: ['', '/flash', '/flash/lib']
[boot.py] INFO: Invoking the Universal MicroPython Application Loader (umal)
[mub] INFO: Python module search path is: ['/flash/lib-mpy-1.11-pycom', '', '/flash', '/flash/lib', '/flash/dist-packages', '/flash/terkin']