Good morning and thank you for posting on the Final Fantasy XIV Technical Support Forums.

If the game forces you to change your name once you move and won't let you change it with the name change service, then there is another character on that world with the same name, even if you can't find it. It's possible that there is a 1.0 character on that world with the same name that won't appear on the lodestone, but I can't tell for certain. Regardless, you will have to choose a different name.

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