How the brain processes a stimulus depends not only on its physical properties but also on contextual factors, such as whether it is predictable, expected, or surprising. Though well characterized using non-invasive means, the microcircuit mechanisms responsible for comparing sensory input and expectations remain poorly understood. We recorded single units and local field potential (LFP) activity from primary visual cortex in awake mice engaged in a visual oddball task. Relative to stimulus onset, we distinguish early (50-200ms) and late (200-400ms) neural response windows, a choice compatible with previously described stages of the mismatch response. In line with predictive-processing accounts, we found that LFP in extra-granular cortical layers (associated with the integration of feedforward and feedback processes) were especially responsive to the mismatch between expected and actual input. Furthermore, a decoding analysis showed that unpredictable (control) or unexpected (deviant) stimuli increase the stimulus-specific information present in the population response compared to expected (standard) stimuli. To investigate single-unit contributions to this population response, we considered neurons with significant orientation selectivity and assessed the stability of orientation coding across response windows and trial types (control, standard, deviant). Surprisingly, we found that orientation preference – a usually stable property of V1 neurons – varied across trial types in 30% of cases. In contrast, only 1.3 % of neurons varied its preferred orientation between consecutive presentations of the same stimulus (standard). This change in orientation preference might indicate a stimulus-specific error processing by a subpopulation of V1 neurons, depending on prior expectations and violations thereof.