Can't change a state using Aiogram python

Question

I need to change state in callback handled

@dp.callback_query_handler(text="ru", state=States.lang)
async def change_lang_ru(call: types.CallbackQuery, state: FSMContext):
    global menu_keyboard
    async with state.proxy() as data:
        data['lang'] = 'ru'
    await call.answer(text="Язык поменялся", show_alert=True)
    print(States.all())
    await States.menu.set()

Actually no error appears but next state doesn't start

INFO:aiogram.contrib.middlewares.logging:Received callback query [ID:1631380781948190838] from user [ID:379835437] for message [ID:123] in chat [private:379835437] with data: ru originally posted by user [ID:5151482169]
INFO:aiogram.contrib.middlewares.logging:Unhandled callback query [ID:1631380781948190838] from user [ID:379835437] for message [ID:123] in chat [private:379835437] with data: ru originally posted by user [ID:5151482169]
INFO:aiogram.contrib.middlewares.logging:Process update [ID:41723130]: [success] (in 6 ms)

This is how my next state is supposed to start

@dp.message_handler(state=States.menu)
async def first_test_state_case_met(message: types.Message):
    await message.reply('First!', reply=False)

And these are my states

class States(StatesGroup):
    lang = State()
    menu = State()

I could not find any answers on this in documentation

Answer 1

In Your example i have an error here:

print(States.all())

AttributeError: type object 'States' has no attribute 'all'

@dp.callback_query_handler(text="ru", state=States.lang)
async def change_lang_ru(call: types.CallbackQuery, state: FSMContext):
    global menu_keyboard
    async with state.proxy() as data:
        data['lang'] = 'ru'
    await call.answer(text="???? ?????????", show_alert=True)
    # print(States.all())
    await States.menu.set()

except this, all other states works, but after States changed to menu state:

await States.menu.set()

you should send message to see the response in the next function, because your next function is a message handler, so it expects a message from you

@dp.message_handler(state=States.menu)
async def first_test_state_case_met(message: types.Message):
    await message.reply('First!', reply=False)

And don't forget to finish your state later