System.PlatformNotSupportedException when using ContentDisposition

[pureggerstefan]

Greetings,

since the .NET5 RC1 update on a Blazor WASM, following lines lead to a System.PlatformNotSupportedException

 private static string GetFilename(IReadOnlyDictionary<string, IEnumerable<string>> headers)
        {
            if (headers.ContainsKey("Content-Disposition"))
            {
                //Exception throws at:
                var contentDisposition = new ContentDisposition(headers["Content-Disposition"].First());

                return contentDisposition.FileName;
            }

            return string.Empty;
        }

I think this is a bug, since the ContentDisposition class documentation says it applies to .NET RC1.

Best regards,
Stefan

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[stephentoub]

cc: @akoeplinger, @marek-safar

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[MaximLipnin]

JFR - System.Net.Mail has been modified to throw PNSE at assembly level on Browser (see #38207)

[marek-safar]

Yes, we will probably have to exclude ContentDisposition from that if it's also used by System.Net.Http headers

[LaughingJohn]

I've just stumbled over this as well. Different scenario - I was using MailAddress in Blazor webassembly to validate an email address and it stopped working when I converted it to .Net 5.0. It used to work with .Net core.

            try
            {
                new MailAddress(emailAdddress);
            }
            catch
            {
                return false;
            }

[kjpou1]

Looking into this. Thanks for the report.

[kjpou1]

Closed by #42974

[karelz]

Fixed in 6.0/master (PR #42974) and in 5.0 (PR #43213).