I am fairly new to this, but this is what I found
You need to revert to earlier versions of ldb-tools libldb1 and python-ldb See-
https://tracker.zentyal.org/issues/2505This part is quoted from the tracker--
You need to downgrade the packages incorrectly installed. For doing this please, check that this three packages
ldb-tools libldb1 python-ldb
Are in version 1:1.1.16-1 instead of version 1:1.1.17-1
How to force the downgrade?
sudo apt-get install $PACKAGE_NAME=1:1.1.16-1
Doing that for the three packages should solve your problems.
That also means that you can't update these three packages again.