What operating system are you using?
What symbol(s) are affected in your version? (The current library has no symbol named DIODE or DIODESCH. Edit: none of the 4.0.x tagged device libraries has one of these symbols.)
Is your local kicad library the same as the one taged as 4.0.6 in the repo? (download this file and use a diff tool to see if it is identical to the one you have locally. In linux your local copy lives under /usr/share/kicad/library. I'm not sure where it lives in windows but i think it is somewhere under c:/programm files/kicad)
If your local version is different: Is your kicad a fresh install or did you update it from another version. If you updated it, what version had you installed before 4.0.6? Did you update the library? (In most linux distros it is a separate package. In the widows installer you need to tick a box to update the library)