The underlying connection was closed An unexpected error occurred on a receive

Question

I have the following code   private Uri currentUri   private void Form1 Load object sender  EventArgs e        currentUri   new Uri   http   www stackoverflow com        HttpWebRequest myRequest    HttpWebRequest  HttpWebRequest Create  http   www stackoverflow com        WebProxy myProxy   new WebProxy  120 198 230 8 81        myRequest Proxy   myProxy       HttpWebResponse myResponse    HttpWebResponse myRequest GetResponse         webBrowser1 DocumentStream   myResponse GetResponseStream         webBrowser1 Navigating    new WebBrowserNavigatingEventHandler webBrowser1 Navigating      void webBrowser1 Navigating object sender  WebBrowserNavigatingEventArgs e        if  e Url AbsolutePath     blank                 currentUri   new Uri currentUri  e Url AbsolutePath           HttpWebRequest myRequest    HttpWebRequest HttpWebRequest Create currentUri            HttpWebResponse myResponse    HttpWebResponse myRequest GetResponse             webBrowser1 DocumentStream   myResponse GetResponseStream            e Cancel   true            after compiling      error  An unhandled exception of type  System Net WebException    occurred in System dll      Additional information  The underlying connection was closed  An   unexpected error occurred on a receive    at line HttpWebResponse myResponse    HttpWebResponse myRequest GetResponse     Please help me

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To expand on Bartho Bernsmann s answer  I should like to add that one can have a universal  future-proof implementation at the expense of a little reflection  static void AllowAllSecurityPrototols       int                  i  n      Array                types      SecurityProtocolType combined       types   Enum GetValues  typeof  SecurityProtocolType           combined     SecurityProtocolType  types GetValue  0         n   types Length      for  i   1  i  lt  n  i    1           combined      SecurityProtocolType  types GetValue  i            ServicePointManager SecurityProtocol   combined     I invoke this method in the static constructor of the class that accesses the internet

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My Hosting server block requesting URL And code site getting the same error Unable to read data from the transport connection  An existing connection was forcibly closed by the remote host   --- gt  System Net Sockets SocketException  An existing connection was forcibly closed by the remote host  After a lot of time spent and apply the following step to resolve this issue  Added line before the call web URL ServicePointManager SecurityProtocol   SecurityProtocolType Tls12    SecurityProtocolType Tls11   SecurityProtocolType Tls   still issue not resolve then I upgrade  net version to 4 7 2 but I think it s optional  Last change I have checked my hosting server security level which causes to TLS handshaking for this used  quot https   www ssllabs com ssltest index html quot  site and also check to request URL security level then I find the difference is requested URL have to enable a weak level Cipher Suites you can see in the below image    Now here are my hosting server supporting Cipher Suites  here is called if you have control over requesting URL host server then you can sync this both server Cipher Suites  but in my case  it s not possible so I have applied the following script in Windows PowerShell on my hosting server for enabling required weak level Cipher Suites  Enable-TlsCipherSuite -Name  quot TLS ECDHE RSA WITH AES 256 CBC SHA384 quot   Enable-TlsCipherSuite -Name  quot TLS ECDHE RSA WITH AES 128 CBC SHA256 quot  Enable-TlsCipherSuite -Name  quot TLS ECDHE RSA WITH AES 256 CBC SHA quot  Enable-TlsCipherSuite -Name  quot TLS ECDHE RSA WITH AES 128 CBC SHA quot  Enable-TlsCipherSuite -Name  quot TLS DHE RSA WITH AES 256 CBC SHA quot  Enable-TlsCipherSuite -Name  quot TLS DHE RSA WITH AES 128 CBC SHA quot  Enable-TlsCipherSuite -Name  quot TLS RSA WITH AES 256 GCM SHA384 quot  Enable-TlsCipherSuite -Name  quot TLS RSA WITH AES 128 GCM SHA256 quot  Enable-TlsCipherSuite -Name  quot TLS RSA WITH AES 256 CBC SHA256 quot  Enable-TlsCipherSuite -Name  quot TLS RSA WITH AES 128 CBC SHA256 quot  Enable-TlsCipherSuite -Name  quot TLS RSA WITH AES 256 CBC SHA quot  Enable-TlsCipherSuite -Name  quot TLS RSA WITH AES 256 CBC SHA quot  after applying the above script my hosting server Cipher Suites level look like  Then my issue resolved  Note  server security level downgrade is not a recommended option

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None of the solutions out there worked for me   What I eventually discovered was the following combination    Client system  Windows XP Pro SP3 Client system has  NET Framework 2 SP1  3  3 5 installed Software targeting  NET 2 using classic web services   asmx  Server  IIS6 Web site  Secure Communications  set to    Require Secure Channel Accept client certificates      Apparently  it was this last option that was causing the issue   I discovered this by trying to open the web service URL directly in Internet Explorer  It just hung indefinitely trying to load the page   Disabling  Accept client certificates  allowed the page to load normally   I am not sure if it was a problem with this specific system  maybe a glitched client certificate    Since I wasn t using client certificates this option worked for me

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Setting the HttpWebRequest KeepAlive to false didn t work for me    Since I was accessing a HTTPS page I had to set the Service Point Security Protocol to Tls12    ServicePointManager SecurityProtocol   SecurityProtocolType Tls12    Notice that there are other SecurityProtocolTypes  SecurityProtocolType Ssl3  SecurityProtocolType Tls  SecurityProtocolType Tls11  So if the Tls12 doesn t work for you  try the three remaining options   Also notice that you can set multiple protocols  This is preferable on most cases   ServicePointManager SecurityProtocol   SecurityProtocolType Tls12   SecurityProtocolType Tls11   SecurityProtocolType Tls    Edit  Since this is a choice of security standards it s obviously best to go with the latest  TLS 1 2 as of writing this   and not just doing what works  In fact  SSL3 has been officially prohibited from use since 2015 and TLS 1 0 and TLS 1 1 will likely be prohibited soon as well  source   aske-b

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NET 4 6 and above  You don   t need to do any additional work to support TLS 1 2  it   s supported by default   NET 4 5  TLS 1 2 is supported  but it   s not a default protocol  You need to opt-in to use it  The following code will make TLS 1 2 default  make sure to execute it before making a connection to secured resource   ServicePointManager SecurityProtocol   SecurityProtocolType Tls12  NET 4 0  TLS 1 2 is not supported  but if you have  NET 4 5  or above  installed on the system then you still can opt in for TLS 1 2 even if your application framework doesn   t support it  The only problem is that SecurityProtocolType in  NET 4 0 doesn   t have an entry for TLS1 2  so we   d have to use a numerical representation of this enum value   ServicePointManager SecurityProtocol   SecurityProtocolType Tls12  NET 3 5 or below  TLS 1 2 is not supported  Upgrade your application to more recent version of the framework

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Before Execute query I put the statement as below and it resolved my error  Just FYI in case it will help someone   ServicePointManager SecurityProtocol    SecurityProtocolType 3072                  ctx ExecuteQuery

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I was working also on web scraping project and same issue found  below code applied and it worked nicely  If you are not aware about TLS versions then you can apply all below otherwise you can apply specific    ServicePointManager SecurityProtocol   SecurityProtocolType Ssl3   SecurityProtocolType Tls12   SecurityProtocolType Tls11

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The underlying connection was closed  An unexpected error occurred on a receive      This problem occurs when the server or another network device   unexpectedly closes an existing Transmission Control Protocol  TCP    connection  This problem may occur when a time-out  value on the   server or on the network device is set too low  To resolve this   problem   see resolutions A  D  E  F  and O  The problem can also   occur if the server resets the connection unexpectedly  such as if an   unhandled exception crashes the server  process  Analyze the server   logs to see if this may be the issue    Resolution  To resolve this problem  make sure that you are using the most recent version of the  NET Framework   Add a method to the class to override the GetWebRequest method  This change lets you access the HttpWebRequest object  If you are using Microsoft Visual C   the new method must be similar to the following   class MyTestService TestService TestService       protected override WebRequest GetWebRequest Uri uri                HttpWebRequest webRequest    HttpWebRequest  base GetWebRequest uri             Setting KeepAlive to false         webRequest KeepAlive   false          return webRequest            Excerpt from KB915599  You receive one or more error messages when you try to make an HTTP request in an application that is built on the  NET Framework 1 1 Service Pack 1

[c#] ..The underlying connection was closed: An unexpected error occurred on a receive

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