  A quantum channel models the interaction between the system we are interested
in and its environment. Such a model can capture the main features of the
interaction but because of the complexity of the environment we can not assume
that it is fully accurate. We study the robustness of quantum error correction
operations against completely unexpected and subsequently undetermined type of
channel uncertainties. We find that a channel-adapted optimal error correction
operation does not only give the best possible channel fidelity but it is more
robust against channel alterations than any other error correction operation.
Our results are valid for Pauli channels and stabilizer codes but based on some
numerical results we believe that very similar conclusions can be drawn also in
the general case.
