Regenerating codes are efficient methods for distributed storage in practical networks where node failures are common. They guarantee low cost data reconstruction and repair through accessing only a predefined number of arbitrary chosen storage nodes in the network. In this work we study the fundamental limits of required total repair bandwidth and the storage capacity of these codes under the assumption that i) both data reconstruction and repair are resilient to the presence of a certain number of erroneous nodes in the network and ii) the number of helper nodes in every repair is not fixed, but is a flexible parameter that can be selected during the run-time. We focus on the minimum repair bandwidth point in this work, propose the associated coding scheme to posses both these extra properties, and prove its optimality.