Recording of errors in regards to the usability of systems has traditionally focused on safety-critical systems and business support systems. This study applies Zapf et al.'s 'Taxonomy of Errors' to a non-work related context, an Online Grocery System. The taxonomy was found to show that similar types of errors were made by all users of such systems. However, the number of errors that were recorded by different user groups varied. This finding was in contrast to previous studies, and supported the common perception that beginner users make a greater number of errors than more experienced users.