XenServer The bootloader for this VM returned an error Unable to access a required file in the specified repository: file:///tmp/cdrom-repo

Lovely, yes? It reads: Error: Starting VM 'Ubuntu Precise Pangolin 12.04 (64-bit) (2)' - The bootloader for this VM returned an error -- did the VM installation succeed?  INVALID_SOURCE
Unable to access a required file in the specified repository: file:///tmp/cdrom-repo-cHT3xP/install/vmlinuz.

What this means in simple terms is that the Virtual Machine is not configured to boot from an ISO.

[root@xenserver-aipuwzhh ~]# xe vm-list 
uuid ( RO)           : f5870ba2-c405-56a9-8022-41ca4fc362a1
     name-label ( RW): Ubuntu Precise Pangolin 12.04 (64-bit) (2)
    power-state ( RO): halted


uuid ( RO)           : 77c6963c-fb55-48e2-a799-82ea166d0748
     name-label ( RW): Control domain on host: xenserver-aipuwzhh
    power-state ( RO): running


uuid ( RO)           : 89ddbb9d-4c9e-16c6-1349-ba9b5babae0b
     name-label ( RW): Ubuntu Precise Pangolin 12.04 (64-bit) (1)
    power-state ( RO): running

As we already know, the VM I want to "fix" in my case is the Ubuntu Precise Pangolin 12.04 (64-bit) (2), with the uuid f5870ba2-c405-56a9-8022-41ca4fc362a1. On with the fix then:

[root@xenserver-aipuwzhh ~]# xe vm-param-set uuid=f5870ba2-c405-56a9-8022-41ca4fc362a1 HVM-boot-policy=BIOS\ order HVM-boot-params:order=dc

Drumroll please...

Great stuff.