I am running High Sierra with Clover. I was dual booting with Manjaro Linux. I was trying different flavors of Linux and so wanted to replace my Manjaro with Ubuntu, but I made the mistake of trying to do this from memory instead of re-reading the UEFI multiboot with separate drives guide, and I did the default Ubuntu install. Now my system boots straight to Ubuntu, and when I disconnect the Ubuntu drive, I get the boot0 error and no Clover. AND my boot options in BIOS only show one UEFI option: the Ubuntu option.
With the Ubuntu drive removed, I tried reinstalling Clover by making a Unibeast USB, booting back into the MacOS disk and going thru the Clover Configurator. No luck. So I restored an old config.plist from when I first upgraded to High Sierra. No luck. So I reran Multibeast and re-installed Clover (I didn't delete any pre-existing Clover files. I wasn't sure what to delete. No luck. I noticed that the EFI partition on the MacOS side had a Ubuntu folder, so I deleted it. Still no luck. That's when I removed the Ubuntu drive and started getting the boot0 errors.
I assume that my boot files have gone into the EFI partition on the Linux drive, but am not sure, nor am I sure how to fix this. Is this primarily a boot0 issue, or a Clover/EFI issue? I'm simply not sure where to go from here.
And, BTW, I tried the first boot0 fix and like some others, got the "no such file or directory." In my case, it's because there is no file named boot1h in /usr/standalone/i386.
Core i7 3770
GA-H77N-WIFI
500 Gb Samsung EVO 850 SSD(MacOS)
500 GB WD Blue SSD (Linux)