Background: Despite the growing interest in knowledge brokering as an approach to mobilising knowledge for societal benefit, research has only recently begun investigating the consequences of knowledge brokers' actions. In particular, while it is known that failure can provide a valuable learning experience for individuals and organisations alike, very few studies have explored failure in knowledge brokering. Aims and objectives: With the aim of informing how knowledge brokers can navigate common professional challenges, this article discusses a spectrum of reasons for failure in the professional practice of knowledge brokering. Methods: Data for this article comes from a developmental evaluation of a network of knowledge brokers, focusing specifically on a set of semi-structured interviews (N = 20). Findings: The overarching themes identified in this study are organised according to the three constructs that knowledge brokers act upon in the i-PARIHS framework: innovation, recipients, and context. Knowledge brokers experienced different types of failure across these constructs, ranging from violations of prescribed practices and processes to exploratory testing. Discussion and conclusions: Failure is not a monolithic outcome, and future research could seek to identify levers for change regarding the failure experiences available to knowledge brokers. Additionally, it will not be enough to learn to fail; research and practice in knowledge brokering must learn to fail "intelligently." Finally, failure cannot remain a private experience. Advancing the field of knowledge brokering will require researchers and practitioners to share when and how their efforts have failed.