Invalid library

Complier outputs "invalid library.." 
These are nice but superficial info messages since the libraries are not used. 

1. What makes library "invalid" ?
2. Is there an option to turn this "invalid library " message off? 


code]Invalid library found in /home/jim/Arduino/libraries/USB_MSC_Minimal: /home/jim/Arduino/libraries/USB_MSC_Minimal
Invalid library found in /home/jim/Arduino/libraries/minmsc_2013_11_27_v1_1: /home/jim/Arduino/libraries/minmsc_2013_11_27_v1_1
Invalid library found in /home/jim/Arduino/libraries/UHS30: /home/jim/Arduino/libraries/UHS30
Invalid library found in /home/jim/Arduino/libraries/UTFT: /home/jim/Arduino/libraries/UTFT
Invalid library found in /home/jim/Arduino/libraries/TFT_V2: /home/jim/Arduino/libraries/TFT_V2
Invalid library found in /home/jim/Arduino/libraries/FATS: /home/jim/Arduino/libraries/FATS

julyjim:

  1. What makes library “invalid” ?

If the folder contains a sketch instead of a library that’s considered invalid.

If the library is in a subfolder, rather than in the root of the library folder, that’s considered invalid.

julyjim:
2. Is there an option to turn this "invalid library " message off?

No, you either need to fix the problem or use Arduino IDE 1.6.5-r5 or previous(the warning was added in 1.6.6).

The solution is to move any non-libraries out of the libraries folder and fix any libraries that have an incorrect folder structure. Either way they aren’t doing you any good in the libraries folder as is. I could probably help you with this process but I’d need a screenshot or directory listing of the contents of those folders to give you specific instructions.

Thank, now I know the cause I can find the cure.