Comment by Merad

I've upgraded apps from every version since .Net Core 2.0. The upgrades always take a few hours, maybe half a day (with the exception of 2.0 to 3.0 which took a few days - many breaking changes). It's well worth a few hours per year to get the advantages of newer languages features, enhancements in Asp.Net Core, security and performance enhancements in the .Net Runtime, etc.