According to Crane Brinton's respected "Theory of Revolution," all revolutions have certain symptoms in common. A common condition of all of these symptoms is an ineffective government. Revolutions happen when the government is unwilling or unable to meet the basic needs of its citizens. People across all socioeconomic classes become unhappy with the government and will unify and overthrow said government.
Often times the anger directed towards governments is due to irresponsibility in terms of its fiscal policies. Governments that are overthrown often cannot organize their finances correctly and are either going bankrupt or trying to tax the citizens heavily and unjustly.
Another quality shared by revolutions is that the government has stripped citizens of basic human and civil rights. The citizens become disillusioned by unacceptable restrictions in the economy, society, or religion.
In short, all revolutions have this in common: citizens are unhappy with the actions of its government.