An apparatus comprises at least three processing circuits to perform redundant processing of common program instructions. Error detection circuitry coupled to a plurality of signal nodes of each of said at least three processing circuits comprises comparison circuitry to detect a mismatch between signals on corresponding signal nodes in said at least three processing circuits, the plurality of signal nodes forming a first group of signal nodes and a second group of signal nodes. In response to the mismatch being detected in relation to corresponding signal nodes within the first group, the error detection circuitry is configured to generate a first trigger for a full recovery process for resolving an error detected for an erroneous processing circuit using state information derived from at least two other processing circuits. In response to the mismatch being detected in relation to corresponding signal nodes within the second group the error detection circuitry is configured to generate a second trigger for a targeted recovery process for a subset of components of the erroneous processing circuit. By implementing a targeted recovery process for a subset of components of an erroneous processing circuit a cheaper recovery process may be provided.