September 16, 2020
.NET Framework 3.5 and 4.7.2
The September 16, 2020 update for Windows 10, version 1809 and Windows Server, version 2019 includes cumulative reliability improvements in .NET Framework 3.5 and 4.7.2. We recommend that you apply this update as part of your regular maintenance routines. Before you install this update, see the Prerequisites and Restart requirement sections.
Quality and reliability improvements
- Addressed a failure that sometimes occured when a user connects to one Azure SQL database, performed an enclave based operation, and then connected to another database under the same server that has the same Attestation URL and performed an enclave operation on the second server.
- Added a CLR config variable Thread_AssignCpuGroups (1 by default) that can be set to 0 to disable automatic CPU group assignment done by the CLR for new threads created by Thread.Start() and thread pool threads, such that an app may do its own thread-spreading.
- Addressed a rare data corruption that can occur when using new API’s such as Unsafe.ByteOffset<T> which are often used with the new Span types. The corruption could occur when a GC operation is performed while a thread is calling Unsafe.ByteOffset<T> from inside of a loop.
- Addressed an issue regarding timers with very long due times ticking down much sooner than expected when the AppContext switch "Switch.System.Threading.UseNetCoreTimer" is enabled.
- Disabled resuse of AppPathModifier in ASP.Net control output.
- HttpCookie objects in the ASP.Net request context will be created with configured defaults for cookie flags instead of .NET-style primitive defaults to match the behavior of `new HttpCookie(name)`.
2 Common Language Runtime (CLR)
Known issues in this security update
After you apply this September 16, 2020 Security and Quality Rollup for .NET Framework 4.8, some ASP.Net applications fail during precompilation. The error message that you receive will likely contain the words “Error ASPCONFIG.”
An invalid configuration state in either the “sessionState,” “anonymouseIdentification,” or “authentication/forms” sections of “System.web” configuration. This might occur during build-and-publish routines if configuration transformations leave the Web.config file in an intermediate state for precompilation.
This issue has been resolved in KB4576949.
Additional information about this update
The following articles contain additional information about this update as it relates to individual product versions.
4577324 Description of the Cumulative Update Preview for .NET Framework 3.5, 4.7.2 and 4.8 for Windows 10, version 1809 and Windows Server, version 2019 (KB4577324)
How to obtain and install the update
Install this update
Windows Update and Microsoft Update
To download and install this update, go to Settings > Update & Security > Windows Update, and then select Check for updates.
Microsoft Update Catalog
To get the standalone package for this update, go to the Microsoft Update Catalog website.
Windows Server Update Services (WSUS)
You can import this update into WSUS manually. See the Microsoft Update Catalog for instructions.
For a list of the files that are provided in this update, download the file information for cumulative update.
To apply this update, you must have .NET Framework 3.5 or 4.7.2 installed.
You must restart the computer after you apply this update if any affected files are being used. We recommend that you exit all .NET Framework-based applications before you apply this update.