Today I tried syncing and it failed, see log below. It succeeded when I moved the portfile away. Base is from source.
$ sudo port -v sync ---> Updating the ports tree Synchronizing local ports tree from file:///opt/local/myports Creating port index in /opt/local/myports Total number of ports parsed: 0 Ports successfully parsed: 0 Ports failed: 0 Up-to-date ports skipped: 80 Synchronizing local ports tree from file:///opt/local/var/macports/sources/github.com/macports/macports-ports/ Current branch master is up to date. Creating port index in /opt/local/var/macports/sources/github.com/macports/macports-ports Error: Unable to determine location of a macOS SDK. Failed to parse file editors/textmate2/Portfile: can't read "configure.sdkroot": Unable to determine location of a macOS SDK. Total number of ports parsed: 1 Ports successfully parsed: 0 Ports failed: 1 Up-to-date ports skipped: 19396 Command failed: /opt/local/bin/portindex /opt/local/var/macports/sources/github.com/macports/macports-ports Exit code: 1 Error: updating PortIndex for file:///opt/local/var/macports/sources/github.com/macports/macports-ports/ failed