Wondering how to resolve AWS EC2 Internal error on launch? We can help you.

Here, at Bobcares, we assist our customers with several AWS queries as part of our AWS Support Services.

Today, let us see steps followed by our Support Techs to resolve this EC2 error.

How to resolve AWS EC2 Internal error on launch?

Typical error will look as shown below:

Server.InternalError: Internal error on launch

Usually, you receive this error if duplicate or invalid device mappings are specified in your AWS CloudFormation template.

This issue occurs if the block device mappings in your launch template or launch configuration might contain block device names that are not available or currently not supported.

You can’t have two block devices map to the same location (for example, /dev/sdb).

Please note if you’re using a Nitro-based instance type (for example, c5, m5, or t3), then you won’t receive this error.

Because /dev/sdb and /dev/xvdb are mapped to two different NVMe devices in the operating system.

Today, let us see the method followed by our Support Techs to resolve this error:

Firstly, in the BlockDeviceMappings property of your AWS CloudFormation template, confirm that your block devices aren’t mapping to the same location by checking the value of DeviceName for each block device.

In the following JSON and YAML example templates, the block devices specified are /dev/xvdb and /dev/xvdc.

Then, the root volume is automatically provision for the instance, and the block devices are associate as secondary volumes.

JSON:

"Ec2Instance" : {
"Type" : "AWS::EC2::Instance",
"Properties" : {
"...OtherProperties..."
"BlockDeviceMappings" : [
{
"DeviceName" : "/dev/xvdb",
"Ebs" : { "VolumeSize" : "100" }
},{
"DeviceName" : "/dev/xvdc",
"Ebs" : { "VolumeSize" : "100" }
}
]
}
}

YAML:

EC2Instance:
Type: AWS::EC2::Instance
Properties:
...OtherProperties...
BlockDeviceMappings:
-
DeviceName: /dev/xvdb
Ebs:
VolumeSize: 100
-
DeviceName: /dev/xvdc
Ebs:
VolumeSize: 100

[Need help with the procedure? We’d be glad to assist you]

Conclusion

In short, we saw how our Support Techs resolve this EC2 Internal error on launch.