title: Building a net5.0 targeted app which can run on net6.0 runtime
body: <p>I previously thought the net6.0 runtime was backwards compatible in that net5.0 apps would just run as-is, but that isn't what I'm seeing in testing.  My development system is using VS2019, so it does not support the net6.0 SDK.  I have tried to manually convert the TargetFramework tag to TargetFrameworks and add net5.0;net6.0, but it won't build.  I would love some kind of net5.0+ tag which indicates 5 or later, but I can't find that either.</p>
  <p>But why doesn't TargetFramework set to net5.0 work when deployed to a system with only the net6.0 runtime?  Let's say my app was built before net6.0 existed.  I wouldn't want to have to issue a new package when net6.0 was released.  Would this require the customer to keep net5.0 installed indefinitely to keep supporting my app?</p>
  <p>I feel like I'm missing something simple, but after several hours of reading I'm not any closer to figuring it out.</p>