BACKGROUND:Operational failures, defined as inadequacies or errors in the information, supplies, or equipment needed for patient care, are known to be highly consequential in hospital environments. Despite their likely relevance for GPs' experiences of work, they remain under-explored in primary care. AIM:To identify operational failures in the primary care work environment and to examine how they influence GPs' work. DESIGN AND SETTING:Qualitative interview study in the East of England. METHOD:Semi-structured interviews were conducted with GPs (n = 21). Data analysis was based on the constant comparison method. RESULTS:GPs reported a large burden of operational failures, many of them related to information transfer with external healthcare providers, practice technology, and organisation of work within practices. Faced with operational failures, GPs undertook 'compensatory labour' to fulfil their duties of coordinating and safeguarding patients' care. Dealing with operational failures imposed significant additional strain in the context of already stretched daily schedules, but this work remained largely invisible. In part, this was because GPs acted to fix problems in the here-and-now rather than referring them to source, and they characteristically did not report operational failures at system level. They also identified challenges in making process improvements at practice level, including medicolegal uncertainties about delegation. CONCLUSION:Operational failures in primary care matter for GPs and their experience of work. Compensatory labour is burdensome with an unintended consequence of rendering these failures largely invisible. Recognition of the significance of operational failures should stimulate efforts to make the primary care work environment more attractive.