Microsoft will be shutting down codeplex come December. The official date seems to be the 15th of December 2017. All source code has been moved to GitHub. Codeplex was started in 2006 and was a repository for any developer who wanted to share code with the community.

Link below for more details..

https://blogs.msdn.microsoft.com/bharry/2017/03/31/shutting-down-codeplex/

I hope this article was useful. Have a good day ahead.
Bodhisatya