libsdl_image @1.2.10_3 - Image error: /opt/local/include/SDL/SDL_image.h already exists

[dstwo@…]

I was doing a port upgrade outdated (after doing a port selfupdate) and I got the following error.

sudo port upgrade outdated
Password:
--->  Computing dependencies for supertux
--->  Dependencies to be installed: libsdl_image
--->  Activating libsdl_image @1.2.10_3
Error: Target org.macports.activate returned: Image error: /opt/local/include/SDL/SDL_image.h already exists and does not belong to a registered port.  Unable to activate port libsdl_image. Use 'port -f activate libsdl_image' to force the activation.
Error: Failed to install libsdl_image
Log for libsdl_image is at: /opt/local/var/macports/logs/_opt_local_var_macports_sources_rsync.macports.org_release_ports_devel_libsdl_image/libsdl_image/main.log
Error: The following dependencies were not installed: libsdl_image
Error: Unable to upgrade port: 1
To report a bug, see <http://guide.macports.org/#project.tickets>

[mf2k (Frank Schima)]

In the future, please fill in the Port field and Cc the port maintainer(s).

[jmroot (Joshua Root)]

This is correct behaviour when a file that a port wants to install already exists. Either move the conflicting file(s) first, or force the activation as the message says and they will be renamed automatically.