a wake-up call

”a wake-up call”
If something that happens is a wake-up call, it should make you realise that you need to take action to change a situation; an event that warns someone that they need to deal with an urgent or dangerous problem
بيدار باش، آنچه که باعث آگاهي از خطري شود و نياز به اقدام سريع را هشدار دهد

Example: The poor turnout for the election will hopefully be a wake-up call to the government.
Example: 1971 earthquake was a wake-up call to strengthen the city’s bridges.