French Phrase
Qu'est-ce qui a causé ce problème ?
Meaning
The sentence asks for the origin or cause of a particular issue: “What caused this problem?” It is a neutral‑to‑formal way of seeking an explanation, using the subject‑question structure *qu'est‑ce qui*.
When to use
Use this phrase when you need to identify the source of a difficulty, whether in a work meeting, a classroom discussion, or a casual conversation about a malfunction. It works well in both spoken and written French.
✦Grammar Breakdown
Qu'est-cequiacauséceproblème?
Qu'est-ce
Interrogative phrase meaning “what”; used with “qui” when the question asks for the subject of an action.
qui
Relative pronoun that functions as the subject of the verb in the clause.
a causé
Passé composé of the verb *causer*; auxiliary *avoir* + past participle *causé*.
ce problème
Demonstrative adjective *ce* + noun *problème*; together they point to a specific problem.
🗨In Conversation
Qu'est-ce qui a causé ce problème ?
What caused this problem?
Je pense que c'est le serveur qui a planté.
I think it’s the server that crashed.
✕Common Mistakes
Qu'est-ce que a causé ce problème ?
When the question asks for the subject, use *qui* not *que*.
Qu'est-ce qui a causé de ce problème ?
The verb *causer* does not take the preposition *de* before its direct object.
↔Alternatives
Quelle est la cause de ce problème ?
What is the cause of this problem?
Qu'est-ce qui a entraîné ce problème ?
What led to this problem?
Pourquoi ce problème est‑il survenu ?
Why did this problem occur?
Cultural Tip
The *qu'est‑ce qui* construction is considered slightly more formal than *pourquoi* when you’re asking for a cause. In everyday speech, French speakers often prefer *c’est quoi qui…* in very informal contexts, but that can sound colloquial. Also, avoid using *causé de*; the correct verb is simply *causer* followed by the direct object.