Exclusive: Cloudi Saliba had her bags packed, passport ready and was about to sit on a plane for nine hours to Hawaii to visit her husband's family.

But the Perth woman, 27, was denied boarding on her $1500 flight and her Electronic System for Travel Authorisation (ESTA) visa waiver mysteriously revoked for reasons she can't understand.

Saliba told 9news.com.au she has travelled to the US many times before and her husband Henry Sweeney was born in the states.

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"I purchased the ESTA and it was approved immediately in August 2024," she said.

"They don't have an expiry for two years so it still would have been valid all the way until August next year."

After flying from Perth, Saliba checked into her Hawaiian Airlines flight in Sydney.

This is when the confusing saga began.

As she headed to the gate, an unwelcome email arrived in her inbox.

"And it says 'there's been a change to your ESTA visa," Saliba said.

After checking the US Customs and Border Protection (CBP) app, Saliba saw her travel to the US was no longer "authorised".

It baffled even the airport staff in Sydney.

Do you have a story? Contact reporter April Glover at Google Play.