ATTENTION: Corey here, creator of BugTracker.NET. Please checkout the successor to BugTracker.NET, "Budoco", which is like BugTracker.NET, but runs cross platform and uses PostgreSQL.
https://github.com/ctrager/budoco
In November 2020 Microsoft released .NET 5, aka .NET Core aka dotnet core. It drops technologies that BugTracker.NET depends on. Budoco is a rewrite that runs on dotnet core. Budoco is *BU*gtracker dot net on *DO*tnet *CO*re.
Microsoft has a good track record of keeping so BugTracker.NET "Classic", which was born in 2001 and is still alive going into 2021, should be fine for the next few years.
So, about BugTracker.NET "Classic":
A web-based bug or issue tracker written using .NET 4.x Framework, ASP.NET, C#, and SQL Server (SQL Server Express too). Probably has all the features you need. Easy to setup. Power and flexibility when you need it. Learn more at http://ifdefined.com/bugtrackernet.html