This is a dream chance - I need to take it with both hands," said Acherberg.
"It's a massive wrench for me to leave Tranmere after so many years, the fans there have always been so great to me and hopefully they always will be.
"I'd like to think that the Tranmere fans will understand my move however as I'm joining one of the best clubs in the world."
Acherberg made over 300 appearances between the sticks for Tranmere.
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