We track bugs, feature requests and other issues in repository where they will get ultimately fixed. If you have a problem and believe that the issue is in CoreCLR itself (native runtime or System.Private.CoreLib base level class library) you should log it on the CoreCLR Issues Page. If in the upper levels of the class library use the CoreFX Issues Page. For all managed API addition proposals use the CoreFX Issues Page and follow the API Review Process.
Before you log a new issue, you should try using the search tool on the issue page on a few keywords to see if the issue was already logged.
If you want to ask a question, or want wider discussion (to see if others share you issue), we encourage you to start a thread in the .NET Foundation forums.
For more real-time feedback you can also start a chat session by clicking on the icons below.
To avoid tipping off malicious users wishing to exploit a vulnerability, security issues and bugs should be reported privately, via email, to the Microsoft Security Response Center (MSRC) secure@microsoft.com. You should receive a response within 24 hours. If for some reason you do not, please follow up via email to ensure we received your original message. Further information, including the MSRC PGP key, can be found in the Security TechCenter
The .NET Core repository is not an appropriate place to log issues for the 'Desktop' .NET Framework built into the Windows operating system. If you are having issues with the Full .NET Framework or .NET Runtime the best ways to file a bug are at Connect or through Product Support if you have a contract.