Odd. I'm not calling for any library in my sketch. Why do I keep getting this error message? (I used Timer.h in a previous sketch).
Here it is:
Invalid library found in C:\Users\Richard\Documents\Arduino\libraries\Timer.h: no headers files (.h) found in C:\Users\Richard\Documents\Arduino\libraries\Timer.h
Invalid library found in C:\Users\Richard\Documents\Arduino\libraries\Timer.h: no headers files (.h) found in C:\Users\Richard\Documents\Arduino\libraries\Timer.h
Invalid library found in C:\Users\Richard\Documents\Arduino\libraries\Timer.h: no headers files (.h) found in C:\Users\Richard\Documents\Arduino\libraries\Timer.h
I don't know why, but until someone cleverer comes along console yourself with the knowledge that I have a similar message, but it does't seem to affect my sketches so far.
My mistake seems to be that I imported some libraries into a folder and gave it a bad name.
The Arduino IDE warns you about invalid libraries every time the libraries are scanned. That happens on every compile and when you open/close Library or Boards Manager. The invalid library won't actually hurt anything, but it could cause you some confusion (and it already has as we know from your previous thread), and likely it slows the library scan process slightly. Plus the warnings are annoying. Since C:\Users\Richard\Documents\Arduino\libraries\Timer.h is not doing you any good, I recommend deleting it.