Infrastructure as a service (IaaS) cloud supports flexible and agile execution of applications by creating virtualized execution environment namely, virtual machines (VMs) with on-demand infrastructural resources. In such environment, VM migration is used as a tool to facilitate system maintenance, load balancing and fault tolerance. The use of VM migration is to establish the portfolio of using dynamic and scalable infrastructure services offered by the service providers. In this paper, we study the VM migration process and investigate the potential faults which can occur during migration. Also, the state changes of a VM throughout its lifetime has been systematically analyzed and modeled as concurrent state machines. The potential faults are presented considering the live migration process of VM and accordingly VM state changes. In addition, a methodology for identifying the migration faults has been presented.