The converter tool
designed to convert MIT App Inventor Classic projects to MIT App Inventor 2 projects has just been released. Note that it is carefully, and specifically designed to convert projects from the latest version of MIT App Inventor Classic to projects readable by MIT App Inventor 2 while maintaining the functionality, but necessarily not the same form of the projects. Make note, project files developed on other App Inventor systems may well not work with the converter tool and will not be supported by the MIT App Inventor team.
Full instructions for using the converter
are available, but the first, and very important step, is to download a copy of your MIT App Inventor Classic project files to your own computer. For each project that you choose to convert, please open it in MIT App Inventor Classic, including opening the blocks, if possible, and then download the source .zip file. After that, follow the instructions
to use the converter for each project file.