openjdk-9-jdk manages to conflict with one of its own dependencies.
$ sudo apt install openjdk-9-jdk
Reading package lists... Done
Building dependency tree
Reading state information... Done
The following additional packages will be installed:
openjdk-9-jdk-headless openjdk-9-jre openjdk-9-jre-headless
Suggested packages:
openjdk-9-demo openjdk-9-source visualvm icedtea-8-plugin fonts-ipafont-gothic fonts-ipafont-mincho fonts-indic
The following NEW packages will be installed
openjdk-9-jdk openjdk-9-jdk-headless openjdk-9-jre openjdk-9-jre-headless
0 to upgrade, 4 to newly install, 0 to remove and 18 not to upgrade.
Need to get 236 MB/237 MB of archives.
After this operation, 364 MB of additional disk space will be used.
Do you want to continue? [Y/n]
Get:1 http://gb.archive.ubuntu.com/ubuntu xenial/universe i386 openjdk-9-jre-headless i386 9~b114-0ubuntu1 [236 MB]
Fetched 236 MB in 1min 3s (3,739 kB/s)
Selecting previously unselected package openjdk-9-jre-headless:i386.
(Reading database ... 660111 files and directories currently installed.)
Preparing to unpack .../openjdk-9-jre-headless_9~b114-0ubuntu1_i386.deb ...
Unpacking openjdk-9-jre-headless:i386 (9~b114-0ubuntu1) ...
Selecting previously unselected package openjdk-9-jre:i386.
Preparing to unpack .../openjdk-9-jre_9~b114-0ubuntu1_i386.deb ...
Unpacking openjdk-9-jre:i386 (9~b114-0ubuntu1) ...
Selecting previously unselected package openjdk-9-jdk-headless:i386.
Preparing to unpack .../openjdk-9-jdk-headless_9~b114-0ubuntu1_i386.deb ...
Unpacking openjdk-9-jdk-headless:i386 (9~b114-0ubuntu1) ...
Preparing to unpack .../openjdk-9-jdk_9~b114-0ubuntu1_i386.deb ...
Unpacking openjdk-9-jdk:i386 (9~b114-0ubuntu1) ...
dpkg: error processing archive /var/cache/apt/archives/openjdk-9-jdk_9~b114-0ubuntu1_i386.deb (--unpack):
trying to overwrite '/usr/lib/jvm/java-9-openjdk-i386/include/linux/jawt_md.h', which is also in package openjdk-9-jdk-headless:i386 9~b114-0ubuntu1
Processing triggers for bamfdaemon (0.5.3~bzr0+16.04.20180209-0ubuntu1) ...
Rebuilding /usr/share/applications/bamf-2.index...
Processing triggers for desktop-file-utils (0.22-1ubuntu5.1) ...
Processing triggers for mime-support (3.59ubuntu1) ...
Processing triggers for hicolor-icon-theme (0.15-0ubuntu1) ...
Errors were encountered while processing:
/var/cache/apt/archives/openjdk-9-jdk_9~b114-0ubuntu1_i386.deb
E: Sub-process /usr/bin/dpkg returned an error code (1)
This looks identical to Bug #1550950 except that bug is claimed to be fixed.
Status changed to 'Confirmed' because the bug affects multiple users.