Failed to mount rootfs on a bare metal instance

Hi,

I am trying to install Xen hypervisor on a bare-metal instance. After installing Xen, I rebooted the instance but it failed to boot. Below is the system logs. Why was it not able to mount the rootfs? The storage was the same one that the instance was using before installing Xen.

[   80.425165] VFS: Cannot open root device "UUID=436cf32d-5e3d-46ca-b557-f870c8a25794" or unknown-block(0,0): error -6
[   80.425833] Please append a correct "root=" boot option; here are the available partitions:
[   80.426365] 103:00000    8388608 nvme0n1 
[   80.426367]  (driver?)
[   80.426784]   103:00002    8387567 nvme0n1p1 24ca9e81-01
[   80.426786] 
[   80.427226] 103:00001    8388608 nvme1n1 
[   80.427228]  (driver?)
[   80.427645] Kernel panic - not syncing: VFS: Unable to mount root fs on unknown-block(0,0)
[   80.428171] CPU: 25 PID: 1 Comm: swapper/0 Not tainted 5.11.0-1027-aws #30~20.04.1-Ubuntu
[   80.428692] Hardware name: Amazon EC2 m5.metal/Not Specified, BIOS 1.0 10/16/2017
[   80.429171] Call Trace:
[   80.429337]  dump_stack+0x74/0x92
[   80.429561]  panic+0x101/0x2e3
[   80.429765]  mount_block_root+0x299/0x31d
[   80.430031]  mount_root+0x38/0x3a
[   80.430250]  prepare_namespace+0x13f/0x18d
[   80.430518]  kernel_init_freeable+0x262/0x288
[   80.430804]  ? rest_init+0xba/0xba
[   80.431031]  kernel_init+0xe/0x116
[   80.431256]  ret_from_fork+0x22/0x30
[   80.431728] Kernel Offset: disabled