"Something went wrong" message when trying to import a mailing list

When I try to import a mailing list I get a message saying "Import Failed, Something went wrong." and I have tried everything I can come up with but can't make work. Someone plss help. 

Note: When trying to import the list I manage to get to the next step where I can preview the list and also mark that everyone on the list accepts marketing. It's only after that step when I press "Import" that I get the message that something went wrong. 

Thanks!

I have the same problem, have tried all troubleshooting and can still not upload a mailing list!

You can try the ideas here - 

 I tried all of those techniques and nothing worked for me, so it looks like i will cancel my email campaigns with squarespace as i cannot do this basic function, smh.

Works fine in Mailchimp...