root:~# apt-get upgrade
Reading package lists... Done
Building dependency tree
Reading state information... Done
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]? y
Setting up mdadm (3.1.4-1+8efb9d1ubuntu6) ...
dpkg: error processing mdadm (--configure):
 subprocess installed post-installation script returned error exit status 20
No apport report written because MaxReports is reached already
                                                              Errors were encountered while processing:
 mdadm
E: Sub-process /usr/bin/dpkg returned an error code (1)
root:~# apt-get upgrade
Reading package lists... Done
Building dependency tree
Reading state information... Done
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]? y
Setting up mdadm (3.1.4-1+8efb9d1ubuntu6) ...
dpkg: error processing mdadm (--configure):
 subprocess installed post-installation script returned error exit status 20
Errors were encountered while processing:
 mdadm
E: Sub-process /usr/bin/dpkg returned an error code (1)
root:~#