The ability to detect and correct action errors is paramount to safe and efficient behavior. Its underlying processes are subject of intense scientific debate. The recent adaptive orienting theory of error processing (AOT) proposes that errors trigger a cascade of processes that purportedly begins with a broad suppression of active motoric and-crucially-cognitive processes. While the motoric effects of errors are well established, an empirical test of their purported suppressive effects on active cognitive processes is still missing. Here, we provide data from seven experiments that clearly demonstrate such effects. Participants maintained information in working memory (WM) and performed different response conflict tasks during the delay period. Motor error commission during the delay period consistently reduced accuracy on the WM probe, demonstrating an error-related impairment of WM maintenance. We discuss the broad theoretical and practical implications of this finding, both for the AOT and beyond. (PsycInfo Database Record (c) 2022 APA, all rights reserved).