$ sudo apt upgrade
Reading package lists... Done
Building dependency tree
Reading state information... Done
Calculating upgrade... Done
The following packages were automatically installed and are no longer required:
  libsimgearcore3.4.0v5 libsimgearscene3.4.0v5 linux-headers-4.4.0-97 linux-headers-4.4.0-97-generic linux-image-4.4.0-97-generic linux-image-extra-4.4.0-97-generic
Use 'sudo apt autoremove' to remove them.
0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.
1 not fully installed or removed.
After this operation, 0 B of additional disk space will be used.
Do you want to continue? [Y/n]
Setting up snapd (2.28.5~14.04) ...
Failed to execute operation: No such file or directory
dpkg: error processing package snapd (--configure):
 subprocess installed post-installation script returned error exit status 1
Errors were encountered while processing:
 snapd
E: Sub-process /usr/bin/dpkg returned an error code (1)