grub-pc freeze during dpkg

[keysman]

Good morning, I have an issue on my Ubuntu Server 16.04 with xen installed. After an unsuccessful safe-upgrade, I'm not able to update the package grub-pc. Let me show you the results of some statements:


root@jasmin /home/keysman # aptitude update
Hit http://mirror.hetzner.de/ubuntu/packages xenial InRelease
Hit http://mirror.hetzner.de/ubuntu/packages xenial-backports InRelease
Hit http://mirror.hetzner.de/ubuntu/packages xenial-updates InRelease
Hit http://mirror.hetzner.de/ubuntu/security xenial-security InRelease
Hit http://de.archive.ubuntu.com/ubuntu xenial InRelease
Hit http://de.archive.ubuntu.com/ubuntu xenial-updates InRelease
Hit http://de.archive.ubuntu.com/ubuntu xenial-backports InRelease
Get: 1 http://security.ubuntu.com/ubuntu xenial-security InRelease [107 kB]
Fetched 107 kB in 0s (130 kB/s)


root@jasmin /home/keysman # aptitude safe-upgrade
The following partially installed packages will be configured:
grub-pc
No packages will be installed, upgraded, or removed.
0 packages upgraded, 0 newly installed, 0 to remove and 1 not upgraded.
Need to get 0 B of archives. After unpacking 0 B will be used.
Setting up grub-pc (2.02~beta2-36ubuntu3.20) ...
Including Xen overrides from /etc/default/grub.d/xen.cfg
WARNING: GRUB_DEFAULT changed to boot into Xen by default!
Edit /etc/default/grub.d/xen.cfg to avoid this warning.

Now the situation is stalled. Running the ps command in another shell:

root@jasmin /home/keysman # ps auxwww | grep dpkg
root 25563 0.0 0.1 22952 4472 pts/10 Ss+ 09:03 0:00 /usr/bin/dpkg --status-fd 181 --configure grub-pc:amd64
root 25564 0.0 0.4 64784 16760 pts/10 S+ 09:03 0:00 /usr/bin/perl -w /usr/share/debconf/frontend /var/lib/dpkg/info/grub-pc.postinst configure 2.02~beta2-36ubuntu3.17
root 25575 0.0 0.0 15664 3480 pts/10 S+ 09:03 0:00 /bin/bash /var/lib/dpkg/info/grub-pc.postinst configure 2.02~beta2-36ubuntu3.17
root 25675 0.0 0.0 15664 2148 pts/10 S+ 09:03 0:00 /bin/bash /var/lib/dpkg/info/grub-pc.postinst configure 2.02~beta2-36ubuntu3.17
root 26039 0.0 0.0 16976 972 pts/7 S+ 09:06 0:00 grep --color=auto dpkg


Killing the process 25563 and 25564 on the first shell I get the following messages:

E: Sub-process /usr/bin/dpkg exited unexpectedly
W: Operation was interrupted before it could finish
Failed to perform requested operation on package. Trying to recover:
Setting up grub-pc (2.02~beta2-36ubuntu3.20) ...
debconf: DbDriver "config": /var/cache/debconf/config.dat is locked by another process: Resource temporarily unavailable
dpkg: error processing package grub-pc (--configure):
subprocess installed post-installation script returned error exit status 1
Errors were encountered while processing:
grub-pc

Running dpkg --configure -a, I've got the same stalled situation:

root@jasmin /home/keysman # dpkg --configure -a
Setting up grub-pc (2.02~beta2-36ubuntu3.20) ...
Including Xen overrides from /etc/default/grub.d/xen.cfg
WARNING: GRUB_DEFAULT changed to boot into Xen by default!
Edit /etc/default/grub.d/xen.cfg to avoid this warning.


root 26970 0.1 0.1 22944 4400 pts/0 S+ 09:14 0:00 dpkg --configure -a
root 26971 2.8 0.4 64676 16740 pts/0 S+ 09:14 0:00 /usr/bin/perl -w /usr/share/debconf/frontend /var/lib/dpkg/info/grub-pc.postinst configure 2.02~beta2-36ubuntu3.17
root 26982 0.1 0.0 15664 3480 pts/0 S+ 09:14 0:00 /bin/bash /var/lib/dpkg/info/grub-pc.postinst configure 2.02~beta2-36ubuntu3.17
root 27092 0.0 0.0 15664 2212 pts/0 S+ 09:14 0:00 /bin/bash /var/lib/dpkg/info/grub-pc.postinst configure 2.02~beta2-36ubuntu3.17
root 27096 0.0 0.0 16976 1012 pts/7 S+ 09:14 0:00 grep --color=auto dpkg

Can someone help me to fix this issue?

Thanks in advance

vv