I’ve got this problem, too.
After the update has supposedly finished downloading, KS prompted me for the restart. After closing the Katalon Studio I saw some kind of an error message (something like: Katalon update failed, but I’m not 100% sure). Now when I try starting the 5.4.1. version I get the following notice

After I click OK, KS shuts down and if I try to restart it, I get this:
The log file itself says:
!SESSION 2018-06-04 08:26:29.633 -----------------------------------------------
eclipse.buildId=unknown
java.version=1.8.0_102
java.vendor=Oracle Corporation
BootLoader constants: OS=win32, ARCH=x86_64, WS=win32, NL=en_US
Command-line arguments: -os win32 -ws win32 -arch x86_64
!ENTRY org.eclipse.osgi 4 0 2018-06-04 08:26:30.024
!MESSAGE Bundle reference:file:org.eclipse.equinox.simpleconfigurator_1.1.200.v20160504-1450.jar@1:start not found.
!ENTRY org.eclipse.osgi 4 0 2018-06-04 08:26:30.055
!MESSAGE Application error
!STACK 1
java.lang.IllegalStateException: Unable to acquire application service. Ensure that the org.eclipse.core.runtime bundle is resolved and started (see config.ini).
at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.start(EclipseAppLauncher.java:78)
at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:388)
at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:243)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at org.eclipse.equinox.launcher.Main.invokeFramework(Main.java:673)
at org.eclipse.equinox.launcher.Main.basicRun(Main.java:610)
at org.eclipse.equinox.launcher.Main.run(Main.java:1519)
2018-06-04_8-25-48.png
2018-06-04_8-38-56.png