Text-based conversations between users with searchable history in Microsoft Teams Free
Does your friend's name appear correctly in the request, or does it show Unknown User?
Are you having this problem only with this particular person, or with other chat requests as well?
Since you've already tried multiple devices and still get the same error, I don't believe this is a local installation issue.
Let's try something different. Instead of accepting his chat request, open Teams, select New chat, enter your friend's Microsoft account email address, and try sending him a message directly. Does it allow it and can you friend get it?