A DESCRIPTION OF THE PROBLEM :
The following line, typed at the JShell command, crashes the JShell tool: throw new Exception("%s").

C:\tmp>jshell
| Welcome to JShell -- Version 11.0.1
| For an introduction type: /help intro

jshell> throw new Exception("%s")
| Exception java.lang.Exception: Exception in thread "main" java.util.MissingFormatArgumentException: Format specifier '%s'
        at java.base/java.util.Formatter.format(Formatter.java:2672)
        at java.base/java.io.PrintStream.format(PrintStream.java:1053)
        at java.base/java.io.PrintStream.printf(PrintStream.java:949)
        at jdk.jshell/jdk.internal.jshell.tool.JShellTool.error(JShellTool.java:728)
        at jdk.jshell/jdk.internal.jshell.tool.JShellTool.errormsg(JShellTool.java:867)
        at jdk.jshell/jdk.internal.jshell.tool.JShellTool.displayEvalException(JShellTool.java:3451)
        at jdk.jshell/jdk.internal.jshell.tool.JShellTool.displayException(JShellTool.java:3425)
        at jdk.jshell/jdk.internal.jshell.tool.JShellTool.displayException(JShellTool.java:3418)
        at jdk.jshell/jdk.internal.jshell.tool.JShellTool.handleEvent(JShellTool.java:3582)
        at jdk.jshell/jdk.internal.jshell.tool.JShellTool.processSource(JShellTool.java:3550)
        at jdk.jshell/jdk.internal.jshell.tool.JShellTool.processSourceCatchingReset(JShellTool.java:1301)
        at jdk.jshell/jdk.internal.jshell.tool.JShellTool.processInput(JShellTool.java:1203)
        at jdk.jshell/jdk.internal.jshell.tool.JShellTool.run(JShellTool.java:1176)
        at jdk.jshell/jdk.internal.jshell.tool.JShellTool.start(JShellTool.java:975)
        at jdk.jshell/jdk.internal.jshell.tool.JShellToolBuilder.start(JShellToolBuilder.java:254)
        at jdk.jshell/jdk.internal.jshell.tool.JShellToolProvider.main(JShellToolProvider.java:120)

C:\tmp>

This is not entirely contrived. Instead of `throw new Exception` the call that causes JShell to crash could be anything that throws an exception with a detail string that includes a format; for example, Paths.get("\"%s.txt\"") would throw an exception on Windows due to the illegal character, followed by the given path, which includes the "%" sign that causes JShell to crash.

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
Type the following line into JShell command line: throw new Exception("%s").

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
The exception detail message should be printed and the JShell prompt should appear.
ACTUAL -
JShell crashes and returns you to the OS shell command prompt.

CUSTOMER SUBMITTED WORKAROUND :
Be careful not to pass a "%" to any method that may throw an exception with a detail string that includes the passed string. This may not always be possible.

FREQUENCY : always