diff --git a/oslo_log/formatters.py b/oslo_log/formatters.py
index bc1ae0d2..ae2d04d8 100644
--- a/oslo_log/formatters.py
+++ b/oslo_log/formatters.py
@@ -138,17 +138,22 @@ def _get_error_summary(record):
     # If we have an exception, format it to be included in the
     # output.
     if exc_info:
-        # Build the exception summary in the line with the
-        # primary log message, to serve as a mnemonic for error
-        # and warning cases.
-        error_summary = traceback.format_exception_only(
-            exc_info[0],
-            exc_info[1],
-        )[0].rstrip()
-        # Remove the local reference to the exception and
-        # traceback to avoid a memory leak through the frame
-        # references.
-        del exc_info
+        try:
+            # Build the exception summary in the line with the
+            # primary log message, to serve as a mnemonic for error
+            # and warning cases.
+            error_summary = traceback.format_exception_only(
+                exc_info[0],
+                exc_info[1],
+            )[0].rstrip()
+        except TypeError as type_err:
+            # Work around https://bugs.python.org/issue28603
+            error_summary = "<exception with %s>" % six.text_type(type_err)
+        finally:
+            # Remove the local reference to the exception and
+            # traceback to avoid a memory leak through the frame
+            # references.
+            del exc_info
 
     return error_summary
 
@@ -169,7 +174,12 @@ class JSONFormatter(logging.Formatter):
             self.hostname = None
 
     def formatException(self, ei, strip_newlines=True):
-        lines = traceback.format_exception(*ei)
+        try:
+            lines = traceback.format_exception(*ei)
+        except TypeError as type_error:
+            # Work around https://bugs.python.org/issue28603
+            msg = six.text_type(type_error)
+            lines = ['<Unprintable exception due to %s>\n' % msg]
         if strip_newlines:
             lines = [moves.filter(
                 lambda x: x,
@@ -245,7 +255,12 @@ class FluentFormatter(logging.Formatter):
             self.hostname = None
 
     def formatException(self, exc_info, strip_newlines=True):
-        lines = traceback.format_exception(*exc_info)
+        try:
+            lines = traceback.format_exception(*exc_info)
+        except TypeError as type_error:
+            # Work around https://bugs.python.org/issue28603
+            msg = six.text_type(type_error)
+            lines = ['<Unprintable exception due to %s>\n' % msg]
         if strip_newlines:
             lines = reduce(lambda a, line: a + line.rstrip().splitlines(),
                            lines, [])
@@ -450,11 +465,22 @@ class ContextFormatter(logging.Formatter):
     def formatException(self, exc_info, record=None):
         """Format exception output with CONF.logging_exception_prefix."""
         if not record:
-            return logging.Formatter.formatException(self, exc_info)
+            try:
+                return logging.Formatter.formatException(self, exc_info)
+            except TypeError as type_error:
+                # Work around https://bugs.python.org/issue28603
+                msg = six.text_type(type_error)
+                return '<Unprintable exception due to %s>\n' % msg
 
         stringbuffer = moves.StringIO()
-        traceback.print_exception(exc_info[0], exc_info[1], exc_info[2],
-                                  None, stringbuffer)
+        try:
+            traceback.print_exception(exc_info[0], exc_info[1], exc_info[2],
+                                      None, stringbuffer)
+        except TypeError as type_error:
+            # Work around https://bugs.python.org/issue28603
+            msg = six.text_type(type_error)
+            stringbuffer.write('<Unprintable exception due to %s>\n' % msg)
+
         lines = stringbuffer.getvalue().split('\n')
         stringbuffer.close()
 
diff --git a/oslo_log/tests/unit/test_formatters.py b/oslo_log/tests/unit/test_formatters.py
index 3bb2cd45..1a70d6fe 100644
--- a/oslo_log/tests/unit/test_formatters.py
+++ b/oslo_log/tests/unit/test_formatters.py
@@ -16,8 +16,14 @@
 
 import mock
 
+import logging
+import sys
+
+from oslo_config import cfg
+from oslo_config import fixture as config_fixture
 from oslo_context import context
 from oslo_log import formatters
+from oslo_log import log
 from oslotest import base as test_base
 
 
@@ -83,3 +89,55 @@ class FormatterTest(test_base.BaseTestCase):
             'method should be defined for logging context specific '
             'information.  The to_dict() method is deprecated '
             'for oslo.log use.', removal_version='5.0.0', version='3.8.0')
+
+
+# Test for https://bugs.python.org/issue28603
+class FormatUnhashableExceptionTest(test_base.BaseTestCase):
+    def setUp(self):
+        super(FormatUnhashableExceptionTest, self).setUp()
+        self.config_fixture = self.useFixture(
+            config_fixture.Config(cfg.ConfigOpts()))
+        self.conf = self.config_fixture.conf
+        log.register_options(self.conf)
+
+    def _unhashable_exception_info(self):
+        class UnhashableException(Exception):
+            __hash__ = None
+
+        try:
+            raise UnhashableException()
+        except UnhashableException:
+            return sys.exc_info()
+
+    def test_error_summary(self):
+        exc_info = self._unhashable_exception_info()
+        record = logging.LogRecord('test', logging.ERROR, 'test', 0,
+                                   'test message', [], exc_info)
+        err_summary = formatters._get_error_summary(record)
+        self.assertTrue(err_summary)
+
+    def test_json_format_exception(self):
+        exc_info = self._unhashable_exception_info()
+        formatter = formatters.JSONFormatter()
+        tb = ''.join(formatter.formatException(exc_info))
+        self.assertTrue(tb)
+
+    def test_fluent_format_exception(self):
+        exc_info = self._unhashable_exception_info()
+        formatter = formatters.FluentFormatter()
+        tb = formatter.formatException(exc_info)
+        self.assertTrue(tb)
+
+    def test_context_format_exception_norecord(self):
+        exc_info = self._unhashable_exception_info()
+        formatter = formatters.ContextFormatter(config=self.conf)
+        tb = formatter.formatException(exc_info)
+        self.assertTrue(tb)
+
+    def test_context_format_exception(self):
+        exc_info = self._unhashable_exception_info()
+        formatter = formatters.ContextFormatter(config=self.conf)
+        record = logging.LogRecord('test', logging.ERROR, 'test', 0,
+                                   'test message', [], exc_info)
+        tb = formatter.format(record)
+        self.assertTrue(tb)