About the use of être in the two sentences (conveying "What happened to you?")

Question

Which sentence is better for "What happened to you?"

From the FRENCH textbook "le nouveau taxi", leçon 30, there are two expressions:

version old: Qu'est-ce qui vous êtes arrivé?

version new: Qu'est-ce qui vous est arrivé?

I have no idea about the differences between them. Please tell me more.

Answer 1

Yet another update taking into account the OP's new modifications...

The former sentence is incorrect. The latter is the correct one. User @jlliagre provides a good explanation.

Qu'est-ce qui vous est arrivé ? Ce qui m'arrivé...

Another option (rather formal) is

Que vous est-il arrivé ?

To quote user @XouDo: Due to the liaison, both sentences ''Qu'est-ce qui vous êtes arrivé'' and ''Qu'est ce qui vous est arrivé'' would sound the same. But the first one makes no sense.

Answer 2

The second sentence is correct and means "What happened to you?" (Literally: "What is it what happened to you?")

The first sentence is deliberately fooling readers by using the otherwise correct phrase vous êtes arrivé (i.e. You arrived) in a sentence where the pronoun vous is actually not the subject of être but its complement.

As XouDo commented, both forms are pronounced the same way, or at least almost the same way.