MP 1,1-5,1 Requesting guidance to upgrade Mojave as I now have Refindplus and Opencore via *MybootMngr*

[Dayo]

Never actually seen that one before. Will need to check what exactly generates that message.

Seems to do with the ESP being full.
You could mount the ESP and delete any EFI_BAK folder and the EFI/BOOT/vars folder present and clear the trashcan after

 

[Farravi]

You could mount the ESP and delete any EFI_BAK folder

Done

and the EFI/BOOT/vars folder present and clear the trashcan after

No folder in EFI/BOOT called vars.

 

[Dayo]

Empty the trash while the ESP is mounted and try again.

 

[Dayo]

Forgot most likely item filling things up ... delete all the log files and also clear the trash in the same manner.
Do not run debug versions for day to day use afterwards so as not to fill the ESP up