This book presents a selection of papers about problems which arise in dependability studies of contemporary computer systems and networks. Their collection should be an interesting and inspiring source material for scientists, researchers, engineers, and students who must consider diverse dependability characteristics in design, analysis, or maintenance of computer systems and networks. The papers were presented during the 19th DepCoS-RELCOMEX conference which was the next event in a series organized annually since 2006. Originating as a scientific platform for discussions of reliability aspects in computer engineering, the topical scope of the conference has been constantly expanded to incorporate new dependability challenges brought by recent advances in systems and information technologies. Currently, dependable operation in the context of computer processing means obtaining reliable (true and timely) results in the conditions of processing both quantitative and qualitative data, using precise or fuzzy (often: imitating) models and algorithms. With increasing use of artificial intelligence algorithms and tools, dependability in contemporary information technology and computer engineering calls for methods based on cognitive systems and deep learning techniques. Topical variety of the papers included in these proceedings proves that almost all applications of modern computer systems and networks must take into account the aspect of dependability and also illustrates a wide diversity of multidisciplinary subjects which needs to be considered in this context.