Seeing as "everyone" uses Stripe, we can't be the only one experiencing this problem.
When you use Stripe to handle trials, what you actually do is start them on a subscription with an invoice value = 0 with whatever currency you have as your default.
Now of course you don't want your signups to choose what currency they /might/ pay in 30 days later, however once you have assigned an invoice in one currency to a user it is not possible to change the currency.
Most of our users are currently in the UK, so if an EU person signs up they are started on our UK trial. However when they select to pay in EUR they get an error as we can't switch their currency.
How do other SaaS companies who use Stripe for multi-currency subscriptions with free trial periods handle this? Seems only option is not to use Stripe to handle the trial part of a subscription and only create their Stripe account once they want to subscribe.