Exactly what does "failed to process" mean? Does that mean you were watching the battle replay and it abruptly ended? If so maybe you were running up into the 50 round boundary?
However, if it was the battle, the limit would be 100 turns IIRC. After 50 turns, attacker autorouts; some time after that, defender autorouts (75 turns?); and if even more time passes without either side winning or routing, everyone dies.