It could happen that the Euclidean algorithm finds formula_139 of degree higher than formula_223 having number of different roots equal to its degree, where the Fourney formula would be able to correct errors in all its roots, anyway correcting such many errors could be risky (especially with no other restrictions on received word). Usually after getting formula_139 of higher degree, we decide not to correct the errors. Correction could fail in the case formula_139 has roots with higher multiplicity or the number of roots is smaller than its degree. Fail could be detected as well by Forney formula returning error outside the transmitted alphabet.