We had a problem with switching from 2.0 to 2.1 and, of course, it happened when deploying our app to production. We don't practice very good environment management and this was our first .NET Core app to go into production. Dev, QA and UAT were all on 2.0 but when it finally came time to deploy to production 2.1 had been released. 2.1 was installed on prod and we pushed our deployment and there were errors when trying to connect to the site (it was ASP.NET Core web app). We eventually uninstalled 2.1 and installed 2.0 and everything worked but it was frustrating to lose time to that.