The v5.1 HTTPd will not use the v5.0 message file. Sorry for any inconvenience. Some changes in the appearance of script output may be initially disconcerting. The Conan and HyperShelf scripts were extensively reworked to disengage them from dependencies on the WASD HTTPd. Hopefully this does not break any installations out there.
Backward compatibility is maintained.
If this is not in use then they are of no consequence. The v5.0 HTTPd will not use the v4.4 message file. If you have customized it then you will need to carefully compare the two and migrate one into the other somehow. Sorry for any inconvenience. Additional configuration parameters can be supplied to control cache behaviour, logging and scripting environments.