In Marvel: Avengers Alliance multiple errors can occur.
S.H.I.E.L.D. Alert, this error occurs when the game is being worked on.
Simulation Compromised, this occurs when the game registers a 3rd party program that alters in-game data.
Combat Validaton Error, this error occurs when the code of the game does not match what it believes it's supposed to be. This was implemented to stop people from using code altering programs to alter in-game data.
This error is also displayed when the server is being overloaded, judging by it's appearance at the end of a PvP tournament.
Data Post Error, this error occurs when the game can't connect to the server for a certain amount of time while starting up.
Update Error, this occurs when the game registers a change in the currently running game, and the data coming from the server.
When a large change is soon to occur or has recently occured this can continuously trigger, suggesting large amounts of data are continuously uploaded rather than in one large bundle.
Special Operation Expired, this occurs when you are currently positioned in one of the Spec Ops missions, while the countdown has reached 0 Days, 0 Hours, 0 Minutes and 0 Seconds. (give or take 5 Minutes)