When I attempt to run my server on my computer, nobody can join because the client claims it is out of date, even though we are using the latest release (1.8) on both client and server. When I check the logs the server reports the following:

• • • • DETECTED OLD PLAYER DIRECTORY IN THE WORLD SAVE
      • THIS USUALLY HAPPENS WHEN THE AUTOMATIC CONVERSION FAILED IN SOME WAY
  • please restart the server and if the problem persists, remove the directory 'World/players'

I am attempting to load up a world from 1.7.10. And yes, everything works perfectly when running in that version. But every time I try to use in 1.8, the server fails in the same way. I have tried at least four times.