There is described a method for detection of occurrence of printing errors on printed substrates during processing thereof on a printing press comprising the steps of providing multiple sensors on functional components of the printing press to monitor the behavior of the printing press during processing of the printed substrates and performing an in-line analysis of the behavior of the printing press to determine occurrence of a characteristic behavior of the printing press which leads or is likely to lead to occurrence of printing errors on the printed substrates or which leads or is likely to lead to good printing quality of the printed substrates. In-line analysis of the behavior of the printing press preferably includes performing fuzzy pattern classification of the behavior of the printing press. According to one embodiment of the proposed method in-line analysis of the behavior of the printing press is coupled with an in-line optical inspection of the printed substrates.