We address the problem of error correction by linear block codes under the assumption that the syndrome of a received vector is found with errors. We propose a construction of parity-check matrices which allow to solve the syndrome equation even with an erroneous syndrome, in particular, parity-check matrices with minimum redundancy, which are analogs of Reed-Solomon codes for this problem. We also establish analogs of classical coding theory bounds, namely the Hamming, Singleton, and Gilbert-Varshamov bounds. We show that the new problem can be considered as a generalization of the well-known Ulam's problem on searching with a lie and as a discrete analog of the compressed sensing problem.