Recently I tried to update macports and got error:

$ sudo port install MySQL
...
Error: Error installing new MacPorts base: command execution failed
Please run `port -v selfupdate' for details.
Error: /opt/local/bin/port: port selfupdate failed: Error installing new MacPorts base: command execution failed

The fix is:

$ sudo xcode-select --install

Result:

The ports tree has been updated. To upgrade your installed ports, you should run
  port upgrade outdated

cat-yellow

My main background for a recent years is MySQL DEV/DBA engineer but I’m also participating in wider range of tasks which could be likely called as DataOps/DevOps tasks. You can see my online CV here: http://catyellow.net