I am trying to texture paint my object in Blender 2.74 blender-render mode. However, I have noticed that when using a node material, I loose the ability to add new paint slots in material mode. In addition, I keep receiving the message "missing texture slots". Also, clicking on add new paint slot does not resolve the issue, but in other cases this usually solves the problem. After clicking on add new paint slot, Blender does add the new texture in the textures property window, and I can even click on any of those textures in the texture properties window, but it does not activate the texture brush tool and keeps on throwing this error. Now this only happens when I activate a material slot and click on use node in the node editor. In conclusion, I am thinking that it is not possible to texture paint on a node material. Is this so, or is there a way to fix this problem?
It is not possible to paint on a node based material in Blender Render. You can paint on a material in Cycles as nodes as long as you have set up an image node and texture image to paint to - and the best interaction there is in Material Draw mode so that you can see the layers of image textures together.