The outage led some stores to shut down entirely rather than frustrate shoppers, while others handed out treats to make up for the system failure.

Whether or not there’s a deeper explanation for what went wrong, the incident illustrates how Target’s 2013 data breach has shaped its responses to technical problems — it now has to reassure customers even when there’s a relatively mild issue like this. The outage also underscores the fragility of connected retail systems. They can be great when everything’s working, but a lone failure can create headaches for the entire chain.