Portuguese Phrase
O que causou esse problema?
Meaning
Literally “What caused this problem?” – a direct question asking for the origin or reason behind a specific issue that has already been identified.
When to use
Use this sentence when you need to investigate the source of a difficulty, whether in a technical setting (e.g., a software bug) or in everyday life (e.g., a misunderstanding). It works in both formal and informal contexts, though in very formal writing you might prefer “Qual foi a causa desse problema?”.
✦Grammar Breakdown
Oquecausouesseproblema?
Definite article (O)
Masculine singular article used before a noun or pronoun; here it introduces the interrogative phrase.
Interrogative pronoun (que)
Means “what” and is used to ask for information about a thing or event.
Verb (causou)
Past‑perfect (pretérito perfeito) of “causar” – third person singular, indicating a completed action in the past.
Demonstrative adjective (esse)
Points to something that is close to the listener (or already mentioned) – “this/that”.
Noun (problema)
Masculine singular noun meaning “problem”.
Punctuation ( ? )
Marks the sentence as a direct question.
🗨In Conversation
O que causou esse problema?
What caused this problem?
Foi um erro de configuração no servidor.
It was a configuration error on the server.
✕Common Mistakes
O que causar esse problema?
Learners sometimes use the infinitive “causar” after “que”, but the sentence needs the past tense to refer to a completed cause.
O que causou este problema?
“Esse” points to something near the listener; using “este” (near the speaker) can sound odd if the problem is already being discussed.
O que foi a causa desse problema?
In very formal writing, “Qual foi a causa” is preferred; using “O que” in a formal report may be considered too colloquial.
↔Alternatives
Qual foi a causa desse problema?
What was the cause of this problem?
O que originou esse problema?
What originated this problem?
Por que isso aconteceu?
Why did this happen?
Cultural Tip
In Brazilian Portuguese, “o que” is the most common way to ask “what” in everyday speech, while “qual” is slightly more formal and often used when the answer is expected to be a specific item from a known set. Also, Brazilians tend to place the demonstrative “esse/essa” close to the noun to stress that the problem is the one just mentioned or visible to both speakers.