/home/user # apt-get update
...
Get:4 https://downloads.maemo.nokia.com ./ Release [507B]
Err https://downloads.maemo.nokia.com ./ Release
...
The following signatures were invalid: KEYEXPIRED 1349249546 KEYEXPIRED 1349249546 KEYEXPIRED 1349249546
W: You may want to run apt-get update to correct these problems
/home/user # apt-get install yappari
Reading package lists... Done
Building dependency tree
Reading state information... Done
Package yappari is not available, but is referred to by another package.
This may mean that the package is missing, has been obsoleted, or
is only available from another source
E: Package yappari has no installation candidate
/home/user # apt-get install -f
Reading package lists... Done
Building dependency tree
Reading state information... Done
0 upgraded, 0 newly installed, 0 to remove and 22 not upgraded.
/home/