wrt "too many open files", that seems very likely. My own testing with the upgrade ended up with it getting stuck for an extended period of time (30 minutes to an hour, maybe longer), and I just interrupted it with Ctrl+C, whereupon this lovely mess was printed on my terminal: Error in function update Traceback (most recent call last): File "/tmp/ubuntu-release-upgrader-_7m7nofo/DistUpgrade/DistUpgradeController.py", line 1953, in fullUpgrade File "/tmp/ubuntu-release-upgrader-_7m7nofo/DistUpgrade/DistUpgradeController.py", line 1280, in doDistUpgradeSimulation File "/tmp/ubuntu-release-upgrader-_7m7nofo/DistUpgrade/DistUpgradeController.py", line 1306, in doDistUpgrade File "/tmp/ubuntu-release-upgrader-_7m7nofo/DistUpgrade/DistUpgradeCache.py", line 309, in commit File "/usr/lib/python3/dist-packages/apt/cache.py", line 664, in commit File "/usr/lib/python3/dist-packages/apt/cache.py", line 610, in install_archives File "/tmp/ubuntu-release-upgrader-_7m7nofo/DistUpgrade/DistUpgradeView.py", line 229, in run File "/tmp/ubuntu-release-upgrader-_7m7nofo/DistUpgrade/DistUpgradeViewKDE.py", line 532, in wait_child File "/tmp/ubuntu-release-upgrader-_7m7nofo/DistUpgrade/DistUpgradeViewKDE.py", line 528, in update_interface KeyboardInterrupt During handling of the above exception, another exception occurred: Traceback (most recent call last): File "/tmp/ubuntu-release-upgrader-_7m7nofo/DistUpgrade/DistUpgradeViewKDE.py", line 280, in update TypeError: setValue(self, int): argument 1 has unexpected type 'float' Error in sys.excepthook: Traceback (most recent call last): File "/tmp/ubuntu-release-upgrader-_7m7nofo/DistUpgrade/DistUpgradeController.py", line 1953, in fullUpgrade File "/tmp/ubuntu-release-upgrader-_7m7nofo/DistUpgrade/DistUpgradeController.py", line 1280, in doDistUpgradeSimulation File "/tmp/ubuntu-release-upgrader-_7m7nofo/DistUpgrade/DistUpgradeController.py", line 1306, in doDistUpgrade File "/tmp/ubuntu-release-upgrader-_7m7nofo/DistUpgrade/DistUpgradeCache.py", line 309, in commit File "/usr/lib/python3/dist-packages/apt/cache.py", line 664, in commit File "/usr/lib/python3/dist-packages/apt/cache.py", line 610, in install_archives File "/tmp/ubuntu-release-upgrader-_7m7nofo/DistUpgrade/DistUpgradeView.py", line 229, in run File "/tmp/ubuntu-release-upgrader-_7m7nofo/DistUpgrade/DistUpgradeViewKDE.py", line 532, in wait_child File "/tmp/ubuntu-release-upgrader-_7m7nofo/DistUpgrade/DistUpgradeViewKDE.py", line 528, in update_interface KeyboardInterrupt During handling of the above exception, another exception occurred: Traceback (most recent call last): File "/usr/lib/python3/dist-packages/apport_python_hook.py", line 118, in apport_excepthook File "/usr/lib/python3/dist-packages/apport/report.py", line 672, in add_proc_info File "/usr/lib/python3/dist-packages/apport/report.py", line 1800, in get_logind_session OSError: [Errno 24] Too many open files: 'cgroup' Original exception was: Traceback (most recent call last): File "/tmp/ubuntu-release-upgrader-_7m7nofo/DistUpgrade/DistUpgradeController.py", line 1953, in fullUpgrade File "/tmp/ubuntu-release-upgrader-_7m7nofo/DistUpgrade/DistUpgradeController.py", line 1280, in doDistUpgradeSimulation File "/tmp/ubuntu-release-upgrader-_7m7nofo/DistUpgrade/DistUpgradeController.py", line 1306, in doDistUpgrade File "/tmp/ubuntu-release-upgrader-_7m7nofo/DistUpgrade/DistUpgradeCache.py", line 309, in commit File "/usr/lib/python3/dist-packages/apt/cache.py", line 664, in commit File "/usr/lib/python3/dist-packages/apt/cache.py", line 610, in install_archives File "/tmp/ubuntu-release-upgrader-_7m7nofo/DistUpgrade/DistUpgradeView.py", line 229, in run File "/tmp/ubuntu-release-upgrader-_7m7nofo/DistUpgrade/DistUpgradeViewKDE.py", line 532, in wait_child File "/tmp/ubuntu-release-upgrader-_7m7nofo/DistUpgrade/DistUpgradeViewKDE.py", line 528, in update_interface KeyboardInterrupt During handling of the above exception, another exception occurred: Traceback (most recent call last): File "/tmp/ubuntu-release-upgrader-_7m7nofo/DistUpgrade/DistUpgradeViewKDE.py", line 280, in update TypeError: setValue(self, int): argument 1 has unexpected type 'float' Traceback (most recent call last): File "/tmp/ubuntu-release-upgrader-_7m7nofo/DistUpgrade/DistUpgradeController.py", line 1953, in fullUpgrade File "/tmp/ubuntu-release-upgrader-_7m7nofo/DistUpgrade/DistUpgradeController.py", line 1280, in doDistUpgradeSimulation File "/tmp/ubuntu-release-upgrader-_7m7nofo/DistUpgrade/DistUpgradeController.py", line 1306, in doDistUpgrade File "/tmp/ubuntu-release-upgrader-_7m7nofo/DistUpgrade/DistUpgradeCache.py", line 309, in commit File "/usr/lib/python3/dist-packages/apt/cache.py", line 664, in commit File "/usr/lib/python3/dist-packages/apt/cache.py", line 610, in install_archives File "/tmp/ubuntu-release-upgrader-_7m7nofo/DistUpgrade/DistUpgradeView.py", line 229, in run File "/tmp/ubuntu-release-upgrader-_7m7nofo/DistUpgrade/DistUpgradeViewKDE.py", line 532, in wait_child File "/tmp/ubuntu-release-upgrader-_7m7nofo/DistUpgrade/DistUpgradeViewKDE.py", line 528, in update_interface KeyboardInterrupt During handling of the above exception, another exception occurred: Traceback (most recent call last): File "/tmp/ubuntu-release-upgrader-_7m7nofo/kinetic", line 8, in File "/tmp/ubuntu-release-upgrader-_7m7nofo/DistUpgrade/DistUpgradeMain.py", line 241, in main File "/tmp/ubuntu-release-upgrader-_7m7nofo/DistUpgrade/DistUpgradeController.py", line 2042, in run File "/tmp/ubuntu-release-upgrader-_7m7nofo/DistUpgrade/DistUpgradeController.py", line 1971, in fullUpgrade File "/tmp/ubuntu-release-upgrader-_7m7nofo/DistUpgrade/DistUpgradeController.py", line 1532, in abort File "/tmp/ubuntu-release-upgrader-_7m7nofo/DistUpgrade/DistUpgradeController.py", line 207, in openCache File "/tmp/ubuntu-release-upgrader-_7m7nofo/DistUpgrade/DistUpgradeController.py", line 231, in _openCache File "/tmp/ubuntu-release-upgrader-_7m7nofo/DistUpgrade/DistUpgradeCache.py", line 140, in __init__ File "/usr/lib/python3/dist-packages/apt/cache.py", line 152, in __init__ File "/usr/lib/python3/dist-packages/apt/cache.py", line 214, in open apt_pkg.Error: W:Can't create IPC pipe for dpkg call - dpkg (24: Too many open files), E:Unable to mkstemp /tmp/clearsigned.message.qSbmu3 - GetTempFile (24: Too many open files), E:The package lists or status file could not be parsed or opened. Error in sys.excepthook: Traceback (most recent call last): File "/usr/lib/python3/dist-packages/apport_python_hook.py", line 118, in apport_excepthook File "/usr/lib/python3/dist-packages/apport/report.py", line 618, in add_proc_info OSError: [Errno 24] Too many open files: '/proc/1565' Original exception was: Traceback (most recent call last): File "/tmp/ubuntu-release-upgrader-_7m7nofo/DistUpgrade/DistUpgradeController.py", line 1953, in fullUpgrade File "/tmp/ubuntu-release-upgrader-_7m7nofo/DistUpgrade/DistUpgradeController.py", line 1280, in doDistUpgradeSimulation File "/tmp/ubuntu-release-upgrader-_7m7nofo/DistUpgrade/DistUpgradeController.py", line 1306, in doDistUpgrade File "/tmp/ubuntu-release-upgrader-_7m7nofo/DistUpgrade/DistUpgradeCache.py", line 309, in commit File "/usr/lib/python3/dist-packages/apt/cache.py", line 664, in commit File "/usr/lib/python3/dist-packages/apt/cache.py", line 610, in install_archives File "/tmp/ubuntu-release-upgrader-_7m7nofo/DistUpgrade/DistUpgradeView.py", line 229, in run File "/tmp/ubuntu-release-upgrader-_7m7nofo/DistUpgrade/DistUpgradeViewKDE.py", line 532, in wait_child File "/tmp/ubuntu-release-upgrader-_7m7nofo/DistUpgrade/DistUpgradeViewKDE.py", line 528, in update_interface KeyboardInterrupt During handling of the above exception, another exception occurred: Traceback (most recent call last): File "/tmp/ubuntu-release-upgrader-_7m7nofo/kinetic", line 8, in File "/tmp/ubuntu-release-upgrader-_7m7nofo/DistUpgrade/DistUpgradeMain.py", line 241, in main File "/tmp/ubuntu-release-upgrader-_7m7nofo/DistUpgrade/DistUpgradeController.py", line 2042, in run File "/tmp/ubuntu-release-upgrader-_7m7nofo/DistUpgrade/DistUpgradeController.py", line 1971, in fullUpgrade File "/tmp/ubuntu-release-upgrader-_7m7nofo/DistUpgrade/DistUpgradeController.py", line 1532, in abort File "/tmp/ubuntu-release-upgrader-_7m7nofo/DistUpgrade/DistUpgradeController.py", line 207, in openCache File "/tmp/ubuntu-release-upgrader-_7m7nofo/DistUpgrade/DistUpgradeController.py", line 231, in _openCache File "/tmp/ubuntu-release-upgrader-_7m7nofo/DistUpgrade/DistUpgradeCache.py", line 140, in __init__ File "/usr/lib/python3/dist-packages/apt/cache.py", line 152, in __init__ File "/usr/lib/python3/dist-packages/apt/cache.py", line 214, in open apt_pkg.Error: W:Can't create IPC pipe for dpkg call - dpkg (24: Too many open files), E:Unable to mkstemp /tmp/clearsigned.message.qSbmu3 - GetTempFile (24: Too many open files), E:The package lists or status file could not be parsed or opened. The X11 connection broke: No error (code 0) XIO: fatal IO error 2 (No such file or directory) on X server ":0" after 1004 requests (1004 known processed) with 0 events remaining. Note the "dpkg (24: Too many open files)" near the end.