An enterprise resource planning system (ERP-system) is a data system that connects modules within several administrative areas. ERP-systems can give companies the opportunity for increased efficiency since all administrative areas can be managed through one system. However, ERP-systems do not always meet the expectations that the companies have, where it is estimated that only half of the companies manage to realize the benefits that ERP-systems offer. This raises the question why some companies fail in their implementation and how this can be avoided. The purpose is thus to investigate what experiences organizations have taken with them from failed ERP-implementations and through this gain an increased understanding of the causes of critical failure factors and how they can be counteracted. The study has been carried out using a qualitative method where data has been collected through semi-structured interviews with people who have experience in implementing ERP-systems. This is also complemented by previous research which is compiled into a framework used to better understand the collected data. The study states that leadership is often the basis for many of the problems but also the solution to the problems that arise in the implementation, the central aspects of leadership are discussed with the help of previous research as well as empirical findings. One of the most frequently discussed factors by the respondents is involvement, which refers to the difficulties for companies in determining how many and which people should be involved in the implementation. Success in this has a major impact on the internal attitude and receptivity to change. Furthermore, it is stated that there are certain differences between larger and smaller companies, where the smaller companies are more vulnerable to institutional forces. Also, that many organizations experience difficulties in communication with their supplier of the ERP-system, where the system does not meet all the client's needs as a result.