MacPorts Update after macOS Upgrade

After a macOS Upgrade MacPorts does not generally work properly. A fast sudo port selfupdate does not do the work either in almost all cases.

I have very good experience with the following procedure:

1. Download the appropriate MacPorts-Installer for your macOS-version and install it. The old version will be overwritten.
2. Install Xcode Tools (again). In the Terminal: xcode-select –install
   (–install with two -)
   
3. Accept the license in the Terminal with: sudo xcodebuild -license
4. Check MacPorts for updates: sudo port selfupdate. If neccessary this command install the current update.
5. Update installed ports: sudo port upgrade outdated and wait till finished.