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WebServiceDataSource failing to retrieve web resources on TLS 1.2 HTTPS connection


Product Progress® Telerik® Reporting


TLS 1.2 is a relatively new protocol that provides enhanced security. For some Web sources this is the lowest acceptable secure version and all older protocols are disabled. The requirements of TLS 1.2 are recent, and it is not supported by older versions of the .NET Framework. Telerik Reporting code is built against .NET 4.0 mainly for backwards compatibility. The latter does not support TLS 1.2 by default. When using a WebServiceDataSource with such Web sources there may appear a problem with retrieving the data. The reports may throw the following error

The client and server cannot communicate, because they do not possess a common algorithm

Error Message

An error occurred while sending the request.
------------- InnerException -------------
The underlying connection was closed: An unexpected error occurred on a send.
------------- InnerException -------------
Unable to read data from the transport connection: An existing connection was forcibly closed by the remote
------------- InnerException -------------
An existing connection was forcibly closed by the remote host

Suggested Workarounds

To overcome the problem check the Cannot connect to a server by using the ServicePointManager or SslStream APIs after upgrade to the .NET Framework 4.6 Microsoft article, where a workaround is provided.

Workarounds are suggested also in the TLS 1.2 and .NET Support: How to Avoid Connection Errors blog post :

"...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)3072;

...there is also a registry hack which forces 4.5 to use TLS 1.2 by default without enforcing it programmatically."

The workaround cannot be applied to the Standalone designer. Therefore, we introduced an improvement in the latter, starting with Telerik Reporting R3 2018 ( If you need to use the designer with Web services requiring TLS 1.2 it will be necessary to upgrade to at least this version.

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