BGP, the de-facto inter-domain routing protocol, was designed without considering security. Recently, network operators have experienced hijacks of their network prefixes, often due to BGP misconfiguration by other operators, sometimes maliciously. In order to address this, prefix origin validation, based on a RPKI infrastructure, was proposed and developed. Today, many organizations are registering their data in the RPKI to protect their prefixes from accidental mis-origination. However, some organizations submit incorrect information to the RPKI repositories or announce prefixes that do not exactly match what they registered. Also, the RPKI repositories of Internet registries are not operationally reliable. The aim of this work is to reveal these problems via measurement. We show how important they are, try to understand the main causes of errors, and explore possible solutions. In this longitudinal study, we see the impact of a policy which discards route announcements with invalid origins would have on the routing table, and to a lesser extent on the traffic at the edge of a large research network.