After waiting hours for OpenVMS to install on my DEC3000, I was presented with the following error message when I attempted to boot the fresh install:

%APB-F-BADSYSROOT, System root [SYSA.] does not exist, check bootflags

Very disheartening, however it’s a fairly easy fix. My DEC 3000 was previously used for OSF/1 (i.e. UNIX), so a boot parameter was incorrect. BOOT_OSFLAGS was set to A instead of 0,0. I do not yet know exactly what this means, but it’s simple to remedy:

SET BOOT_OSFLAGS 0,0

Viola! The system now boots. I found the solution here.