cordova - What causes the "Windows was unable to communicate with target application" error when building out a Windows 8 app? -

i'm building windows 8 app using cordova in visual studio 2015. i'm using cordova project template comes vs 2015.

the app i'm building has been fine debug builds, has taken longer usual @ times, haven't had issue yet.

i literally updated css , run build , got seemingly generic error "windows unable communicate target application"

after waited moment tried again , worked. i'm getting odd build errors. started doing little changes, css (i using grunt compile sass).

two build errors i've seen www folder not permitted or a file called thumbs.db not copied (however file doesn't exist , never did in folder build references).

i've done android development , can run cleanup fix odd errors sometimes, not sure if need delete files or run command in vs. i've tried starting vs same issues pop at, seems, random times.