Why does my shop not allow customers to enter address?

[emmadavis]

I just opened my shop but I am having some issues with people not being able to complete their order because it gives a shipping address error. 
ex. “This address is not supported. Please choose another.” 

Is this a problem on my end or a potential problem on theirs? 

[TheRealChipA]

Hi @emmadavis.  Can you post your shop’s URL here so i can check it out?  I have an idea what is going on, but I need to test it to be sure.  Thanks!