Kernel panic during EC2 launch

Question

During deployment of new app version on new EC2 with template from AMI image I got following error:

```
[    1.670047] No filesystem could mount root, tried: 
[    1.670048] 
[    1.677170] Kernel panic - not syncing: VFS: Unable to mount root fs on unknown-block(0,0)
[    1.685026] CPU: 1 PID: 1 Comm: swapper/0 Not tainted 4.14.181-140.257.amzn2.x86_64 #1
[    1.692532] Hardware name: Amazon EC2 t3a.nano/, BIOS 1.0 10/16/2017
```

previously it was working like charm - I haven't change any AMI or template setting - just added new SSL certs to nginx

I found this troubleshooting article but cannot move with it since I cannot access instance terminal.

I've tried to boo new instance with add different kernel ID but got this error:

```
You cannot launch multiple AMIs with different virtualization styles at the same time.
```

I believed during AMI kernel has somehow changed and it causes problem - is it possible?

What can cause that issue and how to solve?

Answer

It is impossible to suggest any resolution with the data that you provided. 
I suspect that the issue is related to error in /etc/fstab file.
There might be also an error in launch template for Disk1 and wrong device name
Or the Snapshot / EBS volume is corrupted.

If you added nginx certs then obviously you updated AMI so I suspect there was an issue during new image building process.

Kernel panic during EC2 launch

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