This error can occure when you installed OpenBSD on a Flash Card (for example with a VM and a card reader):
booting hd0a:/bsd: 8404228+1102404 [52+381152+367486]=0x9c7d50 entry point at 0x200120
This happens because the Flash Card had a different name in the VM than it has now in a different computer. OpenBSD was installed with hd0 as the main disk, but it probably has been renamend. So, in the boot loader, set the name right:
set device wd0a # and also set the baud rate while youre already there stty com0 38400 set tty com0
This can be made persistent once the system booted:
$ cat boot.conf # $OpenBSD: boot.conf,v 1.2 1997/08/06 23:14:10 mickey Exp $ # sample boot.conf file set echo timeout in 5 seconds stty com0 38400 set tty com0 set device wd0a
OpenBSD