user25645: When compiling I get the error 
'as: unknown option »-mmcu=avr5« exit status 1' 
I succeeded now using your piece of advise. Thank you so much.

user24064: Delete or rename the old "Arduino15" directory located at /home/(username)/.arduino15    (a.k.a. ~/.arduino15) and re-install 1.6.10.

25645: <p>When compiling I get the error 
'as: unknown option »-mmcu=avr5« exit status 1' </p>

<p>I succeeded now using your piece of advise. Thank you so much.</p>
 24064: <p>Delete or rename the old "Arduino15" directory located at /home/(username)/.arduino15    (a.k.a. ~/.arduino15) and re-install 1.6.10.</p>
