SqlConnection instantiation exception on .NET 4.6 and later after August-September 2018 .NET Framework updates

After you install the August Preview of Quality Rollup or September 11, 2018, .NET Framework update, instantiation of SqlConnection can throw an exception.

Use of a SqlConnection constructor can lead to a stack trace that resembles the following:

Workaround 1

Add the following lines in the configSection of the App.Config file of the application:

<section name="SqlColumnEncryptionEnclaveProviders"
type="System.Data.SqlClient.SqlColumnEncryptionEnclaveProviderConfigurationSection,
System.Data, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" />

Note  If your application doesn't include an app.config file, we recommend that you create and deploy an app.config file that contains this information in the configSection.

If Workaround 1 doesn't work, try Workaround 2.

Workaround 2

Identify a place in the app domain that runs before any objects have been added to the logical call context. Add code to force ConfigurationManager to try to load a section that doesn't exist in any configuration files. For example:

System.Configuration.ConfigurationManager.GetSection("SectionNameThatDoesNotExistInAnyConfigurationFile");

For more information about this issue see the GitHub article Mitigation: Deserialization of objects across app domains.

Microsoft is researching this issue and will provide an update in an upcoming release.