Upgrades with LH, JP, EN, OS, OU, LO and LX are not possible for some particularly favourable offers.

On intercontinental flights, this applies to the following booking classes with:
LOT Polish Airlines (LO) G, L, O, S, T, U, V, W
SWISS (LX) E, K, L, T
Austrian Airlines (OS) E, L, K, T
Lufthansa (LH) E, K, L, P, T, Z
Brussels Airlines (SN) E, G, K, L, T