随机请求已中止：无法创建SSL / TLS安全通道。 返回的代码= MessageAltered
在大约一千个HTTPS请求中的一个中，抛出以下exception：
System.Net.WebException: The request was aborted: Could not create SSL/TLS secure channel. at System.Net.WebClient.DownloadDataInternal(Uri address, WebRequest& request) at System.Net.WebClient.DownloadString(Uri address) System.Net中的日志如下所示：
2016-09-20 15:10:17.1031 | INFO | 72 | System.Net | [2688] Associating HttpWebRequest#37618637 with ServicePoint#28841767 2016-09-20 15:10:17.1031 | INFO | 72 | System.Net | [2688] Associating Connection#16407032 with HttpWebRequest#37618637 2016-09-20 15:10:17.1031 | INFO | 72 | System.Net.Sockets | [2688] Socket#42531032 - Created connection from xxxx:12345 to yyyy:443. 2016-09-20 15:10:17.1031 | INFO | 72 | System.Net | [2688] Connection#16407032 - Created connection from xxxx:12345 to yyyy:443. 2016-09-20 15:10:17.1031 | INFO | 72 | System.Net | [2688] TlsStream#54603865::.ctor(host=www.remoteservice.com, #certs=0) 2016-09-20 15:10:17.1031 | INFO | 72 | System.Net | [2688] Associating HttpWebRequest#37618637 with ConnectStream#27023101 2016-09-20 15:10:17.1031 | INFO | 72 | System.Net | [2688] HttpWebRequest#37618637 - Request: GET /api/v3/method HTTP/1.1 2016-09-20 15:10:17.1031 | INFO | 72 | System.Net | [2688] ConnectStream#27023101 - Sending headers 2016-09-20 15:10:17.1031 | INFO | 72 | System.Net | [2688] SecureChannel#66031633::.ctor(hostname=www.remoteservice.com, #clientCertificates=0, encryptionPolicy=RequireEncryption) 2016-09-20 15:10:17.1031 | INFO | 72 | System.Net | [2688] SecureChannel#66031633 - Left with 0 client certificates to choose from. 2016-09-20 15:10:17.1031 | INFO | 72 | System.Net | [2688] Using the cached credential handle. 2016-09-20 15:10:17.1031 | INFO | 72 | System.Net | [2688] InitializeSecurityContext(credential = System.Net.SafeFreeCredential_SECURITY, context = (null), targetName = www.remoteservice.com, inFlags = ReplayDetect, SequenceDetect, Confidentiality, AllocateMemory, InitManualCredValidation) 2016-09-20 15:10:17.1031 | INFO | 72 | System.Net | [2688] InitializeSecurityContext(In-Buffer length=0, Out-Buffer length=379, returned code=ContinueNeeded). 2016-09-20 15:10:17.1656 | INFO | 72 | System.Net | [2688] InitializeSecurityContext(credential = System.Net.SafeFreeCredential_SECURITY, context = e239863c90:3505f981f0, targetName = www.remoteservice.com, inFlags = ReplayDetect, SequenceDetect, Confidentiality, AllocateMemory, InitManualCredValidation) 2016-09-20 15:10:17.1656 | INFO | 72 | System.Net | [2688] InitializeSecurityContext(In-Buffers count=2, Out-Buffer length=0, returned code=ContinueNeeded). 2016-09-20 15:10:17.1656 | INFO | 72 | System.Net | [2688] InitializeSecurityContext(credential = System.Net.SafeFreeCredential_SECURITY, context = e239863c90:3505f981f0, targetName = www.remoteservice.com, inFlags = ReplayDetect, SequenceDetect, Confidentiality, AllocateMemory, InitManualCredValidation) 2016-09-20 15:10:17.1656 | INFO | 72 | System.Net | [2688] InitializeSecurityContext(In-Buffers count=2, Out-Buffer length=0, returned code=ContinueNeeded). 2016-09-20 15:10:17.1656 | INFO | 72 | System.Net | [2688] InitializeSecurityContext(credential = System.Net.SafeFreeCredential_SECURITY, context = e239863c90:3505f981f0, targetName = www.remoteservice.com, inFlags = ReplayDetect, SequenceDetect, Confidentiality, AllocateMemory, InitManualCredValidation) 2016-09-20 15:10:17.1656 | INFO | 72 | System.Net | [2688] InitializeSecurityContext(In-Buffers count=2, Out-Buffer length=0, returned code=ContinueNeeded). 2016-09-20 15:10:17.1656 | INFO | 72 | System.Net | [2688] InitializeSecurityContext(credential = System.Net.SafeFreeCredential_SECURITY, context = e239863c90:3505f981f0, targetName = www.remoteservice.com, inFlags = ReplayDetect, SequenceDetect, Confidentiality, AllocateMemory, InitManualCredValidation) 2016-09-20 15:10:17.4937 | INFO | 72 | System.Net | [2688] InitializeSecurityContext(In-Buffers count=2, Out-Buffer length=574, returned code=ContinueNeeded). 2016-09-20 15:10:17.5562 | INFO | 72 | System.Net | [2688] InitializeSecurityContext(credential = System.Net.SafeFreeCredential_SECURITY, context = e239863c90:3505f981f0, targetName = www.remoteservice.com, inFlags = ReplayDetect, SequenceDetect, Confidentiality, AllocateMemory, InitManualCredValidation) 2016-09-20 15:10:17.5562 | INFO | 72 | System.Net | [2688] InitializeSecurityContext(In-Buffers count=2, Out-Buffer length=0, returned code=MessageAltered). 2016-09-20 15:10:17.5562 | ERROR | 72 | System.Net | [2688] Exception in HttpWebRequest#37618637:: - The request was aborted: Could not create SSL/TLS secure channel.. 2016-09-20 15:10:17.5562 | ERROR | 72 | System.Net | [2688] Exception in HttpWebRequest#37618637::GetResponse - The request was aborted: Could not create SSL/TLS secure channel.. 2016-09-20 15:10:17.5562 | ERROR | 72 | System.Net | [2688] Exception in HttpWebRequest#37618637:: - The request was aborted: The request was canceled..
InitializeSecurityContext以行结束：
InitializeSecurityContext(In-Buffers count=2, Out-Buffer length=0, returned code=MessageAltered)
要进行比较，这是一个成功的HTTPS调用：
2016-09-20 15:11:21.9128 | INFO | 47 | System.Net | [1900] Associating HttpWebRequest#23767080 with ServicePoint#28841767 2016-09-20 15:11:21.9128 | INFO | 47 | System.Net | [1900] Associating Connection#23643787 with HttpWebRequest#23767080 2016-09-20 15:11:21.9128 | INFO | 47 | System.Net.Sockets | [1900] Socket#66957105 - Created connection from xxxx:12345 to yyyy:443. 2016-09-20 15:11:21.9128 | INFO | 47 | System.Net | [1900] Connection#23643787 - Created connection from xxxx:12345 to yyyy:443. 2016-09-20 15:11:21.9128 | INFO | 47 | System.Net | [1900] TlsStream#51402822::.ctor(host=www.remoteservice.com, #certs=0) 2016-09-20 15:11:21.9128 | INFO | 47 | System.Net | [1900] Associating HttpWebRequest#23767080 with ConnectStream#55741749 2016-09-20 15:11:21.9128 | INFO | 47 | System.Net | [1900] HttpWebRequest#23767080 - Request: GET /api/v3/method/123 HTTP/1.1 2016-09-20 15:11:21.9128 | INFO | 47 | System.Net | [1900] ConnectStream#55741749 - Sending headers 2016-09-20 15:11:21.9128 | INFO | 47 | System.Net | [1900] SecureChannel#20739431::.ctor(hostname=www.remoteservice.com, #clientCertificates=0, encryptionPolicy=RequireEncryption) 2016-09-20 15:11:21.9128 | INFO | 47 | System.Net | [1900] SecureChannel#20739431 - Left with 0 client certificates to choose from. 2016-09-20 15:11:21.9128 | INFO | 47 | System.Net | [1900] Using the cached credential handle. 2016-09-20 15:11:21.9128 | INFO | 47 | System.Net | [1900] InitializeSecurityContext(credential = System.Net.SafeFreeCredential_SECURITY, context = (null), targetName = www.remoteservice.com, inFlags = ReplayDetect, SequenceDetect, Confidentiality, AllocateMemory, InitManualCredValidation) 2016-09-20 15:11:21.9128 | INFO | 47 | System.Net | [1900] InitializeSecurityContext(In-Buffer length=0, Out-Buffer length=379, returned code=ContinueNeeded). 2016-09-20 15:11:21.9909 | INFO | 47 | System.Net | [1900] InitializeSecurityContext(credential = System.Net.SafeFreeCredential_SECURITY, context = e239863c90:3505fb0480, targetName = www.remoteservice.com, inFlags = ReplayDetect, SequenceDetect, Confidentiality, AllocateMemory, InitManualCredValidation) 2016-09-20 15:11:21.9909 | INFO | 47 | System.Net | [1900] InitializeSecurityContext(In-Buffers count=2, Out-Buffer length=0, returned code=ContinueNeeded). 2016-09-20 15:11:21.9909 | INFO | 47 | System.Net | [1900] InitializeSecurityContext(credential = System.Net.SafeFreeCredential_SECURITY, context = e239863c90:3505fb0480, targetName = www.remoteservice.com, inFlags = ReplayDetect, SequenceDetect, Confidentiality, AllocateMemory, InitManualCredValidation) 2016-09-20 15:11:21.9909 | INFO | 47 | System.Net | [1900] InitializeSecurityContext(In-Buffers count=2, Out-Buffer length=0, returned code=ContinueNeeded). 2016-09-20 15:11:21.9909 | INFO | 47 | System.Net | [1900] InitializeSecurityContext(credential = System.Net.SafeFreeCredential_SECURITY, context = e239863c90:3505fb0480, targetName = www.remoteservice.com, inFlags = ReplayDetect, SequenceDetect, Confidentiality, AllocateMemory, InitManualCredValidation) 2016-09-20 15:11:21.9909 | INFO | 47 | System.Net | [1900] InitializeSecurityContext(In-Buffers count=2, Out-Buffer length=0, returned code=ContinueNeeded). 2016-09-20 15:11:21.9909 | INFO | 47 | System.Net | [1900] InitializeSecurityContext(credential = System.Net.SafeFreeCredential_SECURITY, context = e239863c90:3505fb0480, targetName = www.remoteservice.com, inFlags = ReplayDetect, SequenceDetect, Confidentiality, AllocateMemory, InitManualCredValidation) 2016-09-20 15:11:22.3190 | INFO | 47 | System.Net | [1900] InitializeSecurityContext(In-Buffers count=2, Out-Buffer length=574, returned code=ContinueNeeded). 2016-09-20 15:11:22.3815 | INFO | 47 | System.Net | [1900] InitializeSecurityContext(credential = System.Net.SafeFreeCredential_SECURITY, context = e239863c90:3505fb0480, targetName = www.remoteservice.com, inFlags = ReplayDetect, SequenceDetect, Confidentiality, AllocateMemory, InitManualCredValidation) 2016-09-20 15:11:22.7878 | INFO | 47 | System.Net | [1900] InitializeSecurityContext(In-Buffers count=2, Out-Buffer length=0, returned code=ContinueNeeded). 2016-09-20 15:11:22.7878 | INFO | 47 | System.Net | [1900] InitializeSecurityContext(credential = System.Net.SafeFreeCredential_SECURITY, context = e239863c90:3505fb0480, targetName = www.remoteservice.com, inFlags = ReplayDetect, SequenceDetect, Confidentiality, AllocateMemory, InitManualCredValidation) 2016-09-20 15:11:22.7878 | INFO | 47 | System.Net | [1900] InitializeSecurityContext(In-Buffers count=2, Out-Buffer length=0, returned code=ContinueNeeded). 2016-09-20 15:11:22.7878 | INFO | 47 | System.Net | [1900] InitializeSecurityContext(credential = System.Net.SafeFreeCredential_SECURITY, context = e239863c90:3505fb0480, targetName = www.remoteservice.com, inFlags = ReplayDetect, SequenceDetect, Confidentiality, AllocateMemory, InitManualCredValidation) 2016-09-20 15:11:22.7878 | INFO | 47 | System.Net | [1900] InitializeSecurityContext(In-Buffers count=2, Out-Buffer length=0, returned code=OK). 2016-09-20 15:11:22.7878 | INFO | 47 | System.Net | [1900] Remote certificate: [Version] V3 (more info on certificate here) 2016-09-20 15:11:22.7878 | INFO | 47 | System.Net | [1900] SecureChannel#20739431 - Remote certificate was verified as valid by the user. 2016-09-20 15:11:22.7878 | INFO | 47 | System.Net | [1900] ProcessAuthentication(Protocol=Tls12, Cipher=Aes256 256 bit strength, Hash=32781 0 bit strength, Key Exchange=DiffieHellman 4096 bit strength). 2016-09-20 15:11:22.8971 | INFO | 47 | System.Net | [1900] Connection#23643787 - Received status line: Version=1.1, StatusCode=200, StatusDescription=OK. 2016-09-20 15:11:22.8971 | INFO | 47 | System.Net | [1900] Connection#23643787 - Received headers 2016-09-20 15:11:22.8971 | INFO | 47 | System.Net | [1900] ConnectStream#43287324::ConnectStream(Buffered -1 bytes.) 2016-09-20 15:11:22.8971 | INFO | 47 | System.Net | [1900] Associating HttpWebRequest#23767080 with ConnectStream#43287324 2016-09-20 15:11:22.8971 | INFO | 47 | System.Net | [1900] Associating HttpWebRequest#23767080 with HttpWebResponse#32954516 2016-09-20 15:11:22.8971 | INFO | 47 | System.Net | [1900] ContentLength=-1
ServicePointManager配置如下：
ServicePointManager.SecurityProtocol = SecurityProtocolType.Tls12 | SecurityProtocolType.Tls11 | SecurityProtocolType.Tls; ServicePointManager.ServerCertificateValidationCallback = (sender, certificate, chain, errors) => true; ServicePointManager.Expect100Continue = false; ServicePointManager.DefaultConnectionLimit = 24;
.NET框架版本是4.5。
你知道为什么会这样吗？
从Schannel的角度来看，MessageAltered意味着：TLS1_ALERT_BAD_RECORD_MAC，根据RFC 5246： https ：//tools.ietf.org/html/rfc5246表示：
bad_record_mac如果收到的MAC记录不正确，则返回此警报。 如果发送警报，则必须返回此警报，因为TLSCiphertext以无效方式解密：或者它不是块长度的偶数倍，或者在检查时其填充值不正确。 此消息始终是致命的，在正确实现之间的通信中永远不应该被观察到（除非消息在网络中被破坏）。
收到的消息似乎以某种方式/forms被破坏导致错误 – 因为无法执行解密。 您可能需要联系服务器供应商以纠正问题的一方，或者如果您无法影响服务器人员，请重试请求 – 前提是后续请求成功。