1. A method comprises: detecting, by a computing device of a dispersed storage network (DSN), a recovery error when decoding a seemingly valid threshold number of existing encoded data slices of a set of existing encoded data slices, wherein a data segment of a data object was dispersed storage error encoded to produce the set of existing encoded data slices; sending, by the computing device, a notice of the recovery error and a known integrity check value for the data segment to a rebuild module of the DSN; retrieving, by the rebuild module, the set of existing encoded data slices; selectively decoding, by the rebuild module, a different combination of a decode threshold number of existing encoded data slices of the set of existing encoded data slices until the data segment is successfully recovered; dispersed storage error encoding, by the rebuild module, the successfully recovered data segment to produce a set of new encoded data slices; and comparing, by the rebuild module, the seemingly valid threshold number of existing encoded data slices with corresponding new encoded data slices of the set of new encoded data slices on an encoded data slice by encoded data slice basis to identify a corrupted encoded data slice of the seemingly valid threshold number of existing encoded data slices.