diff --git a/letsencrypt/cli.py b/letsencrypt/cli.py
index 118eb6e39..c6df1052c 100644
--- a/letsencrypt/cli.py
+++ b/letsencrypt/cli.py
@@ -98,8 +98,8 @@ def _find_domains(args, installer):
         domains = args.domains
 
     if not domains:
-        sys.exit("Please specify --domains, or --installer that will "
-                 "help in domain names autodiscovery")
+        raise errors.Error("Please specify --domains, or --installer that "
+                           "will help in domain names autodiscovery")
 
     return domains
 
@@ -116,7 +116,8 @@ def _init_acme(config, acc, authenticator, installer):
                 acme.register()
             except errors.LetsEncryptClientError as error:
                 logger.debug(error)
-                sys.exit("Unable to register an account with ACME server")
+                raise errors.Error("Unable to register an account with ACME "
+                                   "server")
 
     return acme
 
@@ -465,6 +466,9 @@ def create_parser(plugins, args):
         "testing", description="The following flags are meant for "
         "testing purposes only! Do NOT change them, unless you "
         "really know what you're doing!")
+    helpful.add(
+        "testing", "--debug", action="store_true",
+        help="Show tracebacks if the program exits abnormally")
     helpful.add(
         "testing", "--no-verify-ssl", action="store_true",
         help=config_help("no_verify_ssl"),
@@ -614,13 +618,8 @@ def _setup_logging(args):
     logger.info("Saving debug log to %s", log_file_name)
 
 
-def main(cli_args=sys.argv[1:]):
-    """Command line argument parsing and main script execution."""
-    # note: arg parser internally handles --help (and exits afterwards)
-    plugins = plugins_disco.PluginsRegistry.find_all()
-    args = create_parser(plugins, cli_args).parse_args(cli_args)
-    config = configuration.NamespaceConfig(args)
-
+def main2(cli_args, args, config, plugins):
+    """Continued main script execution."""
     # Displayer
     if args.text_mode:
         displayer = display_util.FileDisplay(sys.stdout)
@@ -659,5 +658,33 @@ def main(cli_args=sys.argv[1:]):
     return args.func(args, config, plugins)
 
 
+def main(cli_args=sys.argv[1:]):
+    """Command line argument parsing and main script execution."""
+    # note: arg parser internally handles --help (and exits afterwards)
+    plugins = plugins_disco.PluginsRegistry.find_all()
+    args = create_parser(plugins, cli_args).parse_args(cli_args)
+    config = configuration.NamespaceConfig(args)
+
+    def handle_exception_common():
+        """Logs the exception and reraises it if in debug mode."""
+        logger.debug("Exiting abnormally", exc_info=True)
+        if args.debug:
+            raise
+
+    try:
+        return main2(cli_args, args, config, plugins)
+    except errors.Error as error:
+        handle_exception_common()
+        return error
+    except KeyboardInterrupt:
+        handle_exception_common()
+        # Ensures a new line is printed
+        return ""
+    except: # pylint: disable=bare-except
+        handle_exception_common()
+        return ("An unexpected error occured. Please see the logfiles in {0} "
+                "for more details.".format(args.logs_dir))
+
+
 if __name__ == "__main__":
     sys.exit(main())  # pragma: no cover
diff --git a/letsencrypt/tests/cli_test.py b/letsencrypt/tests/cli_test.py
index 1e8e84f6d..6b8f77c62 100644
--- a/letsencrypt/tests/cli_test.py
+++ b/letsencrypt/tests/cli_test.py
@@ -20,13 +20,16 @@ class CLITest(unittest.TestCase):
     def tearDown(self):
         shutil.rmtree(self.tmp_dir)
 
-    def _call(self, args):
+    def _call(self, args, client_mock_attrs=None):
         from letsencrypt import cli
         args = ['--text', '--config-dir', self.config_dir,
                 '--work-dir', self.work_dir, '--logs-dir', self.logs_dir] + args
         with mock.patch('letsencrypt.cli.sys.stdout') as stdout:
             with mock.patch('letsencrypt.cli.sys.stderr') as stderr:
                 with mock.patch('letsencrypt.cli.client') as client:
+                    if client_mock_attrs:
+                        # pylint: disable=star-args
+                        client.configure_mock(**client_mock_attrs)
                     ret = cli.main(args)
         return ret, stdout, stderr, client
 
@@ -55,6 +58,24 @@ class CLITest(unittest.TestCase):
                   for r in xrange(len(flags)))):
             self._call(['plugins',] + list(args))
 
+    def test_exceptions(self):
+        from letsencrypt import errors
+        cmd_arg = ['config_changes']
+        error = [errors.Error('problem')]
+        attrs = {'view_config_changes.side_effect' : error}
+        self.assertRaises(
+            errors.Error, self._call, ['--debug'] + cmd_arg, attrs)
+        self._call(cmd_arg, attrs)
+
+        attrs['view_config_changes.side_effect'] = [KeyboardInterrupt]
+        self.assertRaises(
+            KeyboardInterrupt, self._call, ['--debug'] + cmd_arg, attrs)
+        self._call(cmd_arg, attrs)
+
+        attrs['view_config_changes.side_effect'] = [ValueError]
+        self.assertRaises(
+            ValueError, self._call, ['--debug'] + cmd_arg, attrs)
+        self._call(cmd_arg, attrs)
 
 if __name__ == '__main__':
     unittest.main()  # pragma: no cover