internal storage error

I hav my new htc desire 816g. Its been a month i hav been using it without any problem. But after i updated my software build no. To 1.24.720.001, i m hav this issue that there is "insufficient space on the device" even though i hav 500mb of free space. I hav cleared the cache manually and used 'clean master app' to clean-up my junk. But its not working. I even tried a code '*#9900#' even that does nothing. Please help!! Thanks