We investigated online customer experience formation by using customers’ own explanations of their negative emotions during their online shopping encounters. Survey data from 1,786 Finnish online shoppers were used to identify customers who experienced strong negative emotions during online shopping encounters (N = 215) and the causes of their negative emotions were then analyzed in depth from their written descriptions. Our findings indicated that customers attributed most of their negative emotions to online store characteristics, including user interface, product and service range, pricing, and trustworthiness; however, some negative emotions were also attributable to factors outside of the online store’s control, including individual consumption habits and financial constraints, ecological issues, and family concerns. Our findings demonstrate the multidimensionality of customer experience and highlight the importance of better understanding the different factors that can influence the customer experience.