C HttpWebRequest The underlying connection was closed An unexpected error occurred on a send

Question

I ve been Googling and trying all the solutions I could find or think of myself  The site I m trying to load is running TLS1 2 as is a few other sites I tried to test with to make sure it wasn t a TLS1 2 issue  The other sites loaded fine   byte   buffer   Encoding ASCII GetBytes       mod www amp ssl 1 amp dest account settings ws          amp username     username Replace       20            amp password     password Replace       20       ServicePointManager MaxServicePointIdleTime   1000  ServicePointManager SecurityProtocol   SecurityProtocolType Tls   HttpWebRequest WebReq        HttpWebRequest WebRequest Create           https   secure runescape com m weblogin login ws     WebReq Method    POST   WebReq KeepAlive   false   WebReq Referer        https   secure runescape com m weblogin loginform ws          mod www amp ssl 1 amp expired 0 amp dest account settings ws    WebReq ContentType    application x-www-form-urlencoded   WebReq ContentLength   buffer Length  Stream PostData   WebReq GetRequestStream    PostData Write buffer  0  buffer Length   PostData Close    HttpWebResponse WebResp    HttpWebResponse WebReq GetResponse    Stream Answer   WebResp GetResponseStream    StreamReader  Answer   new StreamReader Answer   reply    Answer ReadToEnd    curAccount    if  reply Contains  Login Successful           eturn true    else        eturn false      No matter what I try I keep getting the exception     The underlying connection was closed  An unexpected error occurred on a send    Under more details I found     Authentication failed because the remote party has closed the transport stream

User · Answer

I experienced this exception  and it was also related to ServicePointManager SecurityProtocol   For me  this was because ServicePointManager SecurityProtocol had been set to Tls   Tls11  because of certain websites the application visits with broken TLS 1 2  and upon visiting a TLS 1 2-only website  tested with SSLLabs  SSL Report   it failed   An option for  NET 4 5 and higher is to enable all TLS versions   ServicePointManager SecurityProtocol   SecurityProtocolType Tls                                        SecurityProtocolType Tls11                                        SecurityProtocolType Tls12

User · Answer

Code for WebTestPlugIn  public class Protocols   WebTestPlugin        public override void PreRequest object sender  PreRequestEventArgs e                ServicePointManager SecurityProtocol   SecurityProtocolType Tls12

User · Answer

Your project supports  Net Framework 4 0 and  Net Framework 4 5  If you have upgrade issues  ServicePointManager SecurityProtocol   SecurityProtocolType Tls12    instead of can use   ServicePointManager SecurityProtocol    SecurityProtocolType 3072

User · Answer

In 4 0 version of the  Net framework the ServicePointManager SecurityProtocol only offered two options to set    Ssl3   Secure Socket Layer  SSL  3 0 security protocol  Tls  Transport Layer Security  TLS  1 0 security protocol   In the next release of the framework the SecurityProtocolType enumerator got extended with the newer Tls protocols  so if your application can use th 4 5 version you can also use    Tls11  Specifies the Transport Layer Security  TLS  1 1 security protocol Tls12  Specifies the Transport Layer Security  TLS  1 2 security protocol    So if you are on  Net 4 5 change your line   ServicePointManager SecurityProtocol   SecurityProtocolType Tls    to   ServicePointManager SecurityProtocol   SecurityProtocolType Tls12    so that the ServicePointManager will create streams that support Tls12 connections   Do notice that the enumeration values can be used as flags so you can combine multiple protocols with a logical OR  ServicePointManager SecurityProtocol   SecurityProtocolType Tls                                           SecurityProtocolType Tls11                                          SecurityProtocolType Tls12    Note Try to keep the number of protocols you support as low as possible and up-to-date with today security standards  Ssll3 is no longer deemed secure and the usage of Tls1 0 SecurityProtocolType Tls is in decline

User · Answer

Enable TLs 1 2 from IE and add the following ServicePointManager SecurityProtocol   SecurityProtocolType Tls12

User · Answer

I had similar issue and the below line helped me solving the issue Thanks to rene  I just pasted this line above the authentication code and it worked  ServicePointManager SecurityProtocol   SecurityProtocolType Tls12

User · Answer

For  Net 4 use   ServicePointManager SecurityProtocol    SecurityProtocolType 768    SecurityProtocolType 3072

[c#] C# HttpWebRequest The underlying connection was closed: An unexpected error occurred on a send

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