What were the long term causes of the french revolution?

the wide social and economic gap between the third estate and the first and second estates

the unfairness of the tax system (first and second estates were exempt)

frustrated ambitions of the growing middle clas to receive social advancements

the influence of the ideas of the Enlightenment (fair government, equality, civil rights)

political ineptitude of the last two absolute monarchs of France (Louis XV and Louis XVI) and a long standing financial crisis in france.