I am working on a old project with .net framework 1.1, it used visual studio 2003 and connected with IIS, I want to upgrade the project to .net framework 2.0 to use some nuget package, How can i upgrade to .net framework 2.0?
You need to be using a version of VS that supports .NET Framework 2.0, which means 2005 or later. Since 2012, Microsoft have provided a free Community edition of VS that has virtually all the features of the Professional edition. Most people should be using a recent, if not the latest, version of that, which is 2022.
If you open such an old project in a new version of VS, you will have to upgrade it. This is a one-way process, so you may want to take a backup. The upgrade process will do that for you. It will change a few files and away you go. You should then be able to simply select a newer .NET version in the project properties.