I have some code below which has always worked fine. So it calls a service called CheckEmail and you pass in an email.

I have noticed though if a “Plus” is in the email it falls over and comes up with a 404 error.

If I have an email like [email protected] it is converted to john.smith%2bnonAdmin1%40aol.com (via urlencode) and it falls over but to me it looks to be convert ok.

If I do not have a plus there is no issue.

using HttpResponseMessage res = await _httpClient.GetAsync($"CheckEmail/{HttpUtility.UrlEncode(userName)}/");
res.EnsureSuccessStatusCode();

I have tried manually altering the + manually (no luck).