hostname - sudo: unable to resolve host Mapi - Ask Ubuntu

when enter sudo su, following error message:

pi@mapi ~ $ sudo su sudo: unable resolve host mapi 

so in /etc/hosts/ , in /etc/hostname hostname mapi exact thame (i check there no space)

pi@mapi ~ $ cat /etc/hosts 127.0.0.1       localhost localhost.localdomain ::1             localhost ip6-localhost ip6-loopback fe00::0         ip6-localnet ff00::0         ip6-mcastprefix ff02::1         ip6-allnodes ff02::2         ip6-allrouters 127.0.1.1       mapi  pi@mapi ~ $ cat /etc/hostname mapi 

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there no spaces:

/ets/hosts /etc/hostnam