# Instance Creation Fails With Error 'Unexpected Build failure Not Rescheduling Build'

## Problem

Instance creation fails with the below error:

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{% tab title="None" %}

```none
ERROR nova.compute.manager [req-uuid [user name]] [instance: [instance-uuid]] Unexpected build failure, not rescheduling build.TRACE nova.compute.manager [instance: [instance-uuid]] MessagingTimeout: Timed out waiting for a reply to message ID fbb7342c8d3147e0b6fc96df9f5250bf
```

{% endtab %}
{% endtabs %}

## Environment

* Platform9 Managed OpenStack All Versions
* Nova
* Libvirtd
* Rabbitmq

## Cause

* The instance was scheduled and created on the host, but failed to update Nova DB as the connection timed out due to a communication issue between ***pf9-ostackhost*** service on the host and ***rabbitmq*** service on the management plane.

List the instances created on the host.

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{% tab title="None" %}

```none
$ sudo virsh list --all
```

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{% endtabs %}

Compare it with the list of instances provided by running below commands.

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{% tab title="None" %}

```none
$ openstack server list --all --host [host_uuid] --fit-width
```

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## Resolution

As this is newly created instance, undefine the affected instance on the host by running below command and try recreating the instance.

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{% tab title="None" %}

```none
$ sudo virsh undefine [instance-uuid]
```

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{% endtabs %}


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