Symbol conversion failure has happened on Solaris-x64 in hotspot/src/share/vm/classfile/javaClasses.cpp:327:
#
# A fatal error has been detected by the Java Runtime Environment:
#
# Internal Error (/scratch/opt/jprt/T/P1/205013.kab/s/hotspot/src/share/vm/classfile/javaClasses.cpp:327), pid=43866, tid=26
# Error: ShouldNotReachHere()
#
# JRE version: Java(TM) SE Runtime Environment (9.0) (fastdebug build 9-internal+0-2016-08-19-205013.kab.hs)
# Java VM: Java HotSpot(TM) 64-Bit Server VM (fastdebug 9-internal+0-2016-08-19-205013.kab.hs, mixed mode, tiered, compressed oops, g1 gc, solaris-amd64)
# Core dump will be written. Default location: /export/home/aurora/sandbox/results/ResultDir/FindClass001/core or core.43866
#
# If you would like to submit a bug report, please visit:
# http://bugreport.java.com/bugreport/crash.jsp
#

JVM crash here(in ShouldNotReachHere()) in hotspot/src/share/vm/classfile/javaClasses.cpp:
Handle java_lang_String::create_from_symbol(Symbol* symbol, TRAPS) {
...
#ifdef ASSERT
  {
    ResourceMark rm;
    const char* expected = symbol->as_utf8();
    char* actual = as_utf8_string(h_obj());
    if (strncmp(expected, actual, utf8_len) != 0) {
      tty->print_cr("Symbol conversion failure: %s --> %s", expected, actual);
      ShouldNotReachHere();
    }
  }
#endif
  return h_obj;
}

Code above has been added by JDK-8141132 "JEP 254: Compact String"