diff --git a/lark/lexer.py b/lark/lexer.py
index 1f1bb752..4291f2d8 100644
--- a/lark/lexer.py
+++ b/lark/lexer.py
@@ -63,7 +63,7 @@ def _get_flags(self, value):
 
 
 class PatternStr(Pattern):
-    __serialize_fields__ = 'value', 'flags'
+    __serialize_fields__ = 'value', 'flags', 'raw'
 
     type: ClassVar[str] = "str"
 
@@ -80,7 +80,7 @@ def max_width(self) -> int:
 
 
 class PatternRE(Pattern):
-    __serialize_fields__ = 'value', 'flags', '_width'
+    __serialize_fields__ = 'value', 'flags', 'raw', '_width'
 
     type: ClassVar[str] = "re"
 
diff --git a/tests/test_cache.py b/tests/test_cache.py
index fd653bff..24e05bb4 100644
--- a/tests/test_cache.py
+++ b/tests/test_cache.py
@@ -3,7 +3,7 @@
 import logging
 from unittest import TestCase, main, skipIf
 
-from lark import Lark, Tree, Transformer
+from lark import Lark, Tree, Transformer, UnexpectedInput
 from lark.lexer import Lexer, Token
 import lark.lark as lark_module
 
@@ -168,7 +168,26 @@ def test_recursive_pattern(self):
         self.assertCountEqual(cm.output, ["ERROR:lark:dummy message"])
 
 
+    def test_error_message(self):
+        # Checks that error message generation works
+        # This is especially important since sometimes the `str` method fails with
+        # the mysterious "<unprintable UnexpectedCharacters object>" or similar
+        g = r"""
+        start: add+
+        add: /\d+/ "+" /\d+/
+        %ignore " "
+        """
+        texts = ("1+", "+1", "", "1 1+1")
 
+        parser1 = Lark(g, parser='lalr', cache=True)
+        parser2 = Lark(g, parser='lalr', cache=True)
+        assert len(self.mock_fs.files) == 1
+        for text in texts:
+            with self.assertRaises((UnexpectedInput)) as cm1:
+                parser1.parse(text)
+            with self.assertRaises((UnexpectedInput)) as cm2:
+                parser2.parse(text)
+            self.assertEqual(str(cm1.exception), str(cm2.exception))
 
 if __name__ == '__main__':
     main()
diff --git a/tests/test_nearley/nearley b/tests/test_nearley/nearley
index 32683168..a46b3747 160000
--- a/tests/test_nearley/nearley
+++ b/tests/test_nearley/nearley
@@ -1 +1 @@
-Subproject commit 326831689826cb1b9a4d21d1ce0d5db9278e9636
+Subproject commit a46b37471db486db0f6e1ce6a2934fb238346b44