I had KNIME 3.4.x working just fine on Ubuntu 17.10.
I updated to KNIME 3.5.1 by downloading the new tarball, rather than using the in-app updater. (Unfortunately I deleted the directory and the tarball of the older 3.4 version when I updated.) The GUI has errors which make it unusable. Please see example screenshots.
The initial launch generates many instances of this error message:
(KNIME:8945): GLib-CRITICAL **: g_base64_encode_step: assertion 'in != NULL' failed
and some other Gtk-CRITICAL and Gtk-WARNING messages.
The "Extension installer" window crops out some buttons (OK, Cancel), though I can hit Return to select the default and continue the install. The installer seems to continue to complete, but then generates a segfault (I have core dumps disabled so there isn't one):
(KNIME:8945): Gtk-WARNING **: Negative content height -3 (allocation 1, extents 2x2) while allocating gadget (node toolbar, owner GtkToolbar)
Gdk-Message: Unable to load x_cursor from the cursor theme
Jan 22, 2018 6:37:54 PM org.apache.cxf.bus.osgi.CXFExtensionBundleListener unregister
INFO: Removing the extensions for bundle 118
1 0x7f22a39497c7 /usr/lib/x86_64-linux-gnu/libjavascriptcoregtk-4.0.so.18(WTFCrash+0x17) [0x7f22a39497c7]
2 0x7f22a898cbd1 /usr/lib/x86_64-linux-gnu/libwebkit2gtk-4.0.so.37(+0x607bd1) [0x7f22a898cbd1]
3 0x7f22a89d2122 /usr/lib/x86_64-linux-gnu/libwebkit2gtk-4.0.so.37(+0x64d122) [0x7f22a89d2122]
4 0x7f22a89d25d9 /usr/lib/x86_64-linux-gnu/libwebkit2gtk-4.0.so.37(+0x64d5d9) [0x7f22a89d25d9]
5 0x7f22a8b89ab0 /usr/lib/x86_64-linux-gnu/libwebkit2gtk-4.0.so.37(+0x804ab0) [0x7f22a8b89ab0]
6 0x7f232e29deb2 /usr/lib/x86_64-linux-gnu/libgobject-2.0.so.0(g_object_unref+0x1a2) [0x7f232e29deb2]
7 0x7f2354387ec0 /lib/x86_64-linux-gnu/libc.so.6(+0x3bec0) [0x7f2354387ec0]
8 0x7f2354387f1a /lib/x86_64-linux-gnu/libc.so.6(+0x3bf1a) [0x7f2354387f1a]
9 0x7f23539e28f7 /home/dwc62/Applications/knime_3.5.1/plugins/org.knime.binary.jre.linux.x86_64_1.8.0.152-01/jre/lib/amd64/server/libjvm.so(+0x6928f7) [0x7f23539e28f7]
10 0x7f2353e28bb5 /home/dwc62/Applications/knime_3.5.1/plugins/org.knime.binary.jre.linux.x86_64_1.8.0.152-01/jre/lib/amd64/server/libjvm.so(+0xad8bb5) [0x7f2353e28bb5]
11 0x7f2353e26f7a /home/dwc62/Applications/knime_3.5.1/plugins/org.knime.binary.jre.linux.x86_64_1.8.0.152-01/jre/lib/amd64/server/libjvm.so(+0xad6f7a) [0x7f2353e26f7a]
12 0x7f2353e272fe /home/dwc62/Applications/knime_3.5.1/plugins/org.knime.binary.jre.linux.x86_64_1.8.0.152-01/jre/lib/amd64/server/libjvm.so(+0xad72fe) [0x7f2353e272fe]
13 0x7f2353e27770 /home/dwc62/Applications/knime_3.5.1/plugins/org.knime.binary.jre.linux.x86_64_1.8.0.152-01/jre/lib/amd64/server/libjvm.so(+0xad7770) [0x7f2353e27770]
14 0x7f2353c7d8d8 /home/dwc62/Applications/knime_3.5.1/plugins/org.knime.binary.jre.linux.x86_64_1.8.0.152-01/jre/lib/amd64/server/libjvm.so(+0x92d8d8) [0x7f2353c7d8d8]
15 0x7f2354b4d7fc /lib/x86_64-linux-gnu/libpthread.so.0(+0x77fc) [0x7f2354b4d7fc]
16 0x7f2354460b5f /lib/x86_64-linux-gnu/libc.so.6(clone+0x3f) [0x7f2354460b5f]
#
# A fatal error has been detected by the Java Runtime Environment:
#
# SIGSEGV (0xb) at pc=0x00007f22a39497cc, pid=8945, tid=0x00007f233c2f2700
#
# JRE version: Java(TM) SE Runtime Environment (8.0_152-b16) (build 1.8.0_152-b16)
# Java VM: Java HotSpot(TM) 64-Bit Server VM (25.152-b16 mixed mode linux-amd64 compressed oops)
# Problematic frame:
# C [libjavascriptcoregtk-4.0.so.18+0xce07cc] WTFCrash+0x1c
#
# Failed to write core dump. Core dumps have been disabled. To enable core dumping, try "ulimit -c unlimited" before starting Java again
#
# An error report file with more information is saved as:
# /home/dwc62/Applications/hs_err_pid8945.log
#
# If you would like to submit a bug report, please visit:
# http://bugreport.java.com/bugreport/crash.jsp
#
I tried also the nightly build knime_3.6.0_2018-01-22_21-20-08 and got the same behavior.