I have a one way ticket to Paris and seeking people who have previously done this. I plan to cycle to Morocco after Europe.
Many told me the airline will not even allow me to board the airplane .
My flight is from Denver to Paris via Norwegian airline.
In progress of contacting them and entry authorities in Paris
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You typically have to show proof of onward passage or funds. Basically, they do not want people arriving and then bumming off the social system. If in doubt from Norwegian, GET IT IN WRITING so there is not "judgement on what to do" at the check-in counter, Another option is to buy a fully refundable (not a credit) 1-way ticket from Paris back to the USA (obviously at least a few weeks after your flight and then cancel for a full refund). More cash up front but can reduce the headaches.
Have a great trip!