json - Python won't handle simple exception

It just wont go into the except block, instead it states there is not such file or directory.. shouldn't it enter in the except block if I get an IOError? what am I missing?

try:
    file_users = open ('datos/usuarios.json','r')
    dic = json.load(file_users)
    file_users.close()
except EOFError, IOError:
    print("File does not exist")