[2020] PINNED: Wipe All The Things for A19

Alpha 19 is not compatible with A18 saves or A18 maps, or with earlier experimental builds of a19. For best results remove all saved data and avoid using the same exact seed name for your A19 map that you used for A18. If your trader is MIA or you have garbled biomes it means you are playing on an old map.

How to Clean out old data:

1. Start the game from your library
   
2. Select show game launcher
   
3. Click in the tools tab
   
4. Click on clean game files and check all circles
   
5. Click clean

Obviously don't do this if you want to play pre-A19 saves or worlds later. Thanks to JOST AMMAN for the suggestion to post this.

P.S. Delete the Mods folder from your client directory to ensure you do not have any old/incompatible mods installed.