diff --git a/pkg/_fe_analyzer_shared/lib/src/messages/codes_generated.dart b/pkg/_fe_analyzer_shared/lib/src/messages/codes_generated.dart
index 40c42a8a3d7..652e463168b 100644
--- a/pkg/_fe_analyzer_shared/lib/src/messages/codes_generated.dart
+++ b/pkg/_fe_analyzer_shared/lib/src/messages/codes_generated.dart
@@ -6113,6 +6113,17 @@ Message _withArgumentsInvalidContinueTarget(String name) {
       arguments: {'name': name});
 }
 
+// DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
+const Code<Null> codeInvalidEscapeStarted = messageInvalidEscapeStarted;
+
+// DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
+const MessageCode messageInvalidEscapeStarted = const MessageCode(
+    "InvalidEscapeStarted",
+    index: 126,
+    problemMessage: r"""The string '\' can't stand alone.""",
+    correctionMessage:
+        r"""Try adding another backslash (\) to escape the '\'.""");
+
 // DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
 const Template<Message Function(String name)>
     templateInvalidGetterSetterTypeFieldContext =
@@ -6438,11 +6449,34 @@ Message _withArgumentsInvalidTypeVariableVariancePositionInReturnType(
 }
 
 // DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
-const Code<Null> codeInvalidUnicodeEscape = messageInvalidUnicodeEscape;
+const Code<Null> codeInvalidUnicodeEscapeUBracket =
+    messageInvalidUnicodeEscapeUBracket;
 
 // DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
-const MessageCode messageInvalidUnicodeEscape = const MessageCode(
-    "InvalidUnicodeEscape",
+const MessageCode messageInvalidUnicodeEscapeUBracket = const MessageCode(
+    "InvalidUnicodeEscapeUBracket",
+    index: 125,
+    problemMessage:
+        r"""An escape sequence starting with '\u{' must be followed by 1 to 6 hexadecimal digits followed by a '}'.""");
+
+// DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
+const Code<Null> codeInvalidUnicodeEscapeUNoBracket =
+    messageInvalidUnicodeEscapeUNoBracket;
+
+// DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
+const MessageCode messageInvalidUnicodeEscapeUNoBracket = const MessageCode(
+    "InvalidUnicodeEscapeUNoBracket",
+    index: 124,
+    problemMessage:
+        r"""An escape sequence starting with '\u' must be followed by 4 hexadecimal digits.""");
+
+// DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
+const Code<Null> codeInvalidUnicodeEscapeUStarted =
+    messageInvalidUnicodeEscapeUStarted;
+
+// DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
+const MessageCode messageInvalidUnicodeEscapeUStarted = const MessageCode(
+    "InvalidUnicodeEscapeUStarted",
     index: 38,
     problemMessage:
         r"""An escape sequence starting with '\u' must be followed by 4 hexadecimal digits or from 1 to 6 digits between '{' and '}'.""");
diff --git a/pkg/_fe_analyzer_shared/lib/src/parser/quote.dart b/pkg/_fe_analyzer_shared/lib/src/parser/quote.dart
index c9ec28a5be9..fe146ce046a 100644
--- a/pkg/_fe_analyzer_shared/lib/src/parser/quote.dart
+++ b/pkg/_fe_analyzer_shared/lib/src/parser/quote.dart
@@ -193,8 +193,9 @@ String unescapeCodeUnits(List<int> codeUnits, bool isRaw, Object location,
       code = $LF;
     } else if (!isRaw && code == $BACKSLASH) {
       if (codeUnits.length == ++i) {
+        // This should only be reachable in error cases.
         listener.handleUnescapeError(
-            codes.messageInvalidUnicodeEscape, location, i, /* length = */ 1);
+            codes.messageInvalidEscapeStarted, location, i, /* length = */ 1);
         return new String.fromCharCodes(codeUnits);
       }
       code = codeUnits[i];
@@ -240,47 +241,78 @@ String unescapeCodeUnits(List<int> codeUnits, bool isRaw, Object location,
       } else if (code == $u) {
         int begin = i;
         if (codeUnits.length == i + 1) {
-          listener.handleUnescapeError(codes.messageInvalidUnicodeEscape,
-              location, begin, codeUnits.length + 1 - begin);
+          listener.handleUnescapeError(
+              codes.messageInvalidUnicodeEscapeUStarted,
+              location,
+              begin,
+              codeUnits.length + 1 - begin);
           return new String.fromCharCodes(codeUnits);
         }
         code = codeUnits[i + 1];
+        bool foundEndBracket = false;
         if (code == $OPEN_CURLY_BRACKET) {
           // Expect 1-6 hex digits followed by '}'.
           if (codeUnits.length == ++i) {
-            listener.handleUnescapeError(codes.messageInvalidUnicodeEscape,
-                location, begin, i + 1 - begin);
+            listener.handleUnescapeError(
+                codes.messageInvalidUnicodeEscapeUBracket,
+                location,
+                begin,
+                i + 1 - begin);
             return new String.fromCharCodes(codeUnits);
           }
           code = 0;
           for (int j = 0; j < 7; j++) {
             if (codeUnits.length == ++i) {
-              listener.handleUnescapeError(codes.messageInvalidUnicodeEscape,
-                  location, begin, i + 1 - begin);
+              listener.handleUnescapeError(
+                  codes.messageInvalidUnicodeEscapeUBracket,
+                  location,
+                  begin,
+                  i + 1 - begin);
               return new String.fromCharCodes(codeUnits);
             }
             int digit = codeUnits[i];
-            if (j != 0 && digit == $CLOSE_CURLY_BRACKET) break;
+            if (j != 0 && digit == $CLOSE_CURLY_BRACKET) {
+              foundEndBracket = true;
+              break;
+            } else if (j == 6) {
+              break;
+            }
             if (!isHexDigit(digit)) {
-              listener.handleUnescapeError(codes.messageInvalidUnicodeEscape,
-                  location, begin, i + 2 - begin);
+              listener.handleUnescapeError(
+                  codes.messageInvalidUnicodeEscapeUBracket,
+                  location,
+                  begin,
+                  i + 2 - begin);
               return new String.fromCharCodes(codeUnits);
             }
             code = (code << 4) + hexDigitValue(digit);
           }
+          if (!foundEndBracket) {
+            listener.handleUnescapeError(
+                codes.messageInvalidUnicodeEscapeUBracket,
+                location,
+                begin,
+                i + 1 - begin);
+          }
         } else {
           // Expect exactly 4 hex digits.
           if (codeUnits.length <= i + 4) {
-            listener.handleUnescapeError(codes.messageInvalidUnicodeEscape,
-                location, begin, codeUnits.length + 1 - begin);
+            listener.handleUnescapeError(
+                codes.messageInvalidUnicodeEscapeUNoBracket,
+                location,
+                begin,
+                codeUnits.length + 1 - begin);
             return new String.fromCharCodes(codeUnits);
           }
           code = 0;
           for (int j = 0; j < 4; j++) {
             int digit = codeUnits[++i];
             if (!isHexDigit(digit)) {
-              listener.handleUnescapeError(codes.messageInvalidUnicodeEscape,
-                  location, begin, i + 1 - begin);
+              listener.handleUnescapeError(
+                  codes.messageInvalidUnicodeEscapeUNoBracket,
+                  location,
+                  begin,
+                  i + 1 - begin);
               return new String.fromCharCodes(codeUnits);
             }
             code = (code << 4) + hexDigitValue(digit);
diff --git a/pkg/analysis_server/lib/src/services/correction/error_fix_status.yaml b/pkg/analysis_server/lib/src/services/correction/error_fix_status.yaml
index c3c7bc1b4f4..41043e5773a 100644
--- a/pkg/analysis_server/lib/src/services/correction/error_fix_status.yaml
+++ b/pkg/analysis_server/lib/src/services/correction/error_fix_status.yaml
@@ -2096,7 +2096,13 @@ ParserErrorCode.INVALID_SYNC:
   status: needsEvaluation
 ParserErrorCode.INVALID_THIS_IN_INITIALIZER:
   status: needsEvaluation
-ParserErrorCode.INVALID_UNICODE_ESCAPE:
+ParserErrorCode.INVALID_UNICODE_ESCAPE_STARTED:
+  status: needsEvaluation
+ParserErrorCode.INVALID_UNICODE_ESCAPE_U_BRACKET:
+  status: needsEvaluation
+ParserErrorCode.INVALID_UNICODE_ESCAPE_U_NO_BRACKET:
+  status: needsEvaluation
+ParserErrorCode.INVALID_UNICODE_ESCAPE_U_STARTED:
   status: needsEvaluation
 ParserErrorCode.INVALID_USE_OF_COVARIANT_IN_EXTENSION:
   status: needsEvaluation
diff --git a/pkg/analyzer/lib/error/error.dart b/pkg/analyzer/lib/error/error.dart
index b28918d4bbf..19f32cc2d1c 100644
--- a/pkg/analyzer/lib/error/error.dart
+++ b/pkg/analyzer/lib/error/error.dart
@@ -805,7 +805,10 @@ const List<ErrorCode> errorCodeValues = [
   ParserErrorCode.INVALID_SUPER_IN_INITIALIZER,
   ParserErrorCode.INVALID_SYNC,
   ParserErrorCode.INVALID_THIS_IN_INITIALIZER,
-  ParserErrorCode.INVALID_UNICODE_ESCAPE,
+  ParserErrorCode.INVALID_UNICODE_ESCAPE_STARTED,
+  ParserErrorCode.INVALID_UNICODE_ESCAPE_U_BRACKET,
+  ParserErrorCode.INVALID_UNICODE_ESCAPE_U_NO_BRACKET,
+  ParserErrorCode.INVALID_UNICODE_ESCAPE_U_STARTED,
   ParserErrorCode.INVALID_USE_OF_COVARIANT_IN_EXTENSION,
   ParserErrorCode.LIBRARY_DIRECTIVE_NOT_FIRST,
   ParserErrorCode.LITERAL_WITH_CLASS_AND_NEW,
diff --git a/pkg/analyzer/lib/src/dart/error/syntactic_errors.g.dart b/pkg/analyzer/lib/src/dart/error/syntactic_errors.g.dart
index 1b0f41cf5b8..41bb5507e3f 100644
--- a/pkg/analyzer/lib/src/dart/error/syntactic_errors.g.dart
+++ b/pkg/analyzer/lib/src/dart/error/syntactic_errors.g.dart
@@ -52,7 +52,7 @@ final fastaAnalyzerErrorCodes = <ErrorCode?>[
   ParserErrorCode.MISSING_ASSIGNABLE_SELECTOR,
   ParserErrorCode.MISSING_INITIALIZER,
   ParserErrorCode.LIBRARY_DIRECTIVE_NOT_FIRST,
-  ParserErrorCode.INVALID_UNICODE_ESCAPE,
+  ParserErrorCode.INVALID_UNICODE_ESCAPE_U_STARTED,
   ParserErrorCode.INVALID_OPERATOR,
   ParserErrorCode.INVALID_HEX_ESCAPE,
   ParserErrorCode.EXPECTED_INSTEAD,
@@ -138,6 +138,9 @@ final fastaAnalyzerErrorCodes = <ErrorCode?>[
   ParserErrorCode.MULTIPLE_CLAUSES,
   ParserErrorCode.OUT_OF_ORDER_CLAUSES,
   ParserErrorCode.UNEXPECTED_TOKENS,
+  ParserErrorCode.INVALID_UNICODE_ESCAPE_U_NO_BRACKET,
+  ParserErrorCode.INVALID_UNICODE_ESCAPE_U_BRACKET,
+  ParserErrorCode.INVALID_UNICODE_ESCAPE_STARTED,
 ];
 
 class ParserErrorCode extends ErrorCode {
@@ -1018,8 +1021,29 @@ class ParserErrorCode extends ErrorCode {
         "'this.namedConstructor())",
   );
 
-  static const ParserErrorCode INVALID_UNICODE_ESCAPE = ParserErrorCode(
-    'INVALID_UNICODE_ESCAPE',
+  static const ParserErrorCode INVALID_UNICODE_ESCAPE_STARTED = ParserErrorCode(
+    'INVALID_UNICODE_ESCAPE_STARTED',
+    "The string '\\' can't stand alone.",
+    correctionMessage: "Try adding another backslash (\\) to escape the '\\'.",
+  );
+
+  static const ParserErrorCode INVALID_UNICODE_ESCAPE_U_BRACKET =
+      ParserErrorCode(
+    'INVALID_UNICODE_ESCAPE_U_BRACKET',
+    "An escape sequence starting with '\\u{' must be followed by 1 to 6 "
+        "hexadecimal digits followed by a '}'.",
+  );
+
+  static const ParserErrorCode INVALID_UNICODE_ESCAPE_U_NO_BRACKET =
+      ParserErrorCode(
+    'INVALID_UNICODE_ESCAPE_U_NO_BRACKET',
+    "An escape sequence starting with '\\u' must be followed by 4 hexadecimal "
+        "digits.",
+  );
+
+  static const ParserErrorCode INVALID_UNICODE_ESCAPE_U_STARTED =
+      ParserErrorCode(
+    'INVALID_UNICODE_ESCAPE_U_STARTED',
     "An escape sequence starting with '\\u' must be followed by 4 hexadecimal "
         "digits or from 1 to 6 digits between '{' and '}'.",
   );
diff --git a/pkg/analyzer/test/generated/error_parser_test.dart b/pkg/analyzer/test/generated/error_parser_test.dart
index 139bb79b0e1..a8779b35d2a 100644
--- a/pkg/analyzer/test/generated/error_parser_test.dart
+++ b/pkg/analyzer/test/generated/error_parser_test.dart
@@ -1705,43 +1705,64 @@ class Wrong<T> {
   void test_invalidUnicodeEscape_incomplete_noDigits() {
     Expression expression = parseStringLiteral("'\\u{'");
     expectNotNullIfNoErrors(expression);
-    listener.assertErrors(
-        [expectedError(ParserErrorCode.INVALID_UNICODE_ESCAPE, 1, 3)]);
+    listener.assertErrors([
+      expectedError(ParserErrorCode.INVALID_UNICODE_ESCAPE_U_BRACKET, 1, 3)
+    ]);
+  }
+
+  void test_invalidUnicodeEscape_incomplete_noDigits_noBracket() {
+    Expression expression = parseStringLiteral("'\\u'");
+    expectNotNullIfNoErrors(expression);
+    listener.assertErrors([
+      expectedError(ParserErrorCode.INVALID_UNICODE_ESCAPE_U_STARTED, 1, 2)
+    ]);
   }
 
   void test_invalidUnicodeEscape_incomplete_someDigits() {
     Expression expression = parseStringLiteral("'\\u{0A'");
     expectNotNullIfNoErrors(expression);
-    listener.assertErrors(
-        [expectedError(ParserErrorCode.INVALID_UNICODE_ESCAPE, 1, 5)]);
+    listener.assertErrors([
+      expectedError(ParserErrorCode.INVALID_UNICODE_ESCAPE_U_BRACKET, 1, 5)
+    ]);
   }
 
   void test_invalidUnicodeEscape_invalidDigit() {
     Expression expression = parseStringLiteral("'\\u0 and some more'");
     expectNotNullIfNoErrors(expression);
+    listener.assertErrors([
+      expectedError(ParserErrorCode.INVALID_UNICODE_ESCAPE_U_NO_BRACKET, 1, 3)
+    ]);
+  }
+
+  void test_invalidUnicodeEscape_too_high_number_variable() {
+    Expression expression = parseStringLiteral("'\\u{110000}'");
+    expectNotNullIfNoErrors(expression);
     listener.assertErrors(
-        [expectedError(ParserErrorCode.INVALID_UNICODE_ESCAPE, 1, 3)]);
+        [expectedError(ParserErrorCode.INVALID_CODE_POINT, 1, 9)]);
   }
 
   void test_invalidUnicodeEscape_tooFewDigits_fixed() {
     Expression expression = parseStringLiteral("'\\u04'");
     expectNotNullIfNoErrors(expression);
-    listener.assertErrors(
-        [expectedError(ParserErrorCode.INVALID_UNICODE_ESCAPE, 1, 4)]);
+    listener.assertErrors([
+      expectedError(ParserErrorCode.INVALID_UNICODE_ESCAPE_U_NO_BRACKET, 1, 4)
+    ]);
   }
 
   void test_invalidUnicodeEscape_tooFewDigits_variable() {
     Expression expression = parseStringLiteral("'\\u{}'");
     expectNotNullIfNoErrors(expression);
-    listener.assertErrors(
-        [expectedError(ParserErrorCode.INVALID_UNICODE_ESCAPE, 1, 4)]);
+    listener.assertErrors([
+      expectedError(ParserErrorCode.INVALID_UNICODE_ESCAPE_U_BRACKET, 1, 4)
+    ]);
   }
 
   void test_invalidUnicodeEscape_tooManyDigits_variable() {
-    Expression expression = parseStringLiteral("'\\u{12345678}'");
+    Expression expression = parseStringLiteral("'\\u{0000000001}'");
     expectNotNullIfNoErrors(expression);
-    listener.assertErrors(
-        [expectedError(ParserErrorCode.INVALID_CODE_POINT, 1, 9)]);
+    listener.assertErrors([
+      expectedError(ParserErrorCode.INVALID_UNICODE_ESCAPE_U_BRACKET, 1, 9)
+    ]);
   }
 
   void test_libraryDirectiveNotFirst() {
diff --git a/pkg/front_end/messages.yaml b/pkg/front_end/messages.yaml
index 730af31f6be..0fcd0f7c52a 100644
--- a/pkg/front_end/messages.yaml
+++ b/pkg/front_end/messages.yaml
@@ -1308,16 +1308,40 @@ InvalidHexEscape:
     - "'\\x0'"
     - "'\\x0y'"
 
-InvalidUnicodeEscape:
+InvalidUnicodeEscapeUStarted:
   index: 38
   problemMessage: "An escape sequence starting with '\\u' must be followed by 4 hexadecimal digits or from 1 to 6 digits between '{' and '}'."
-  analyzerCode: ParserErrorCode.INVALID_UNICODE_ESCAPE
+  analyzerCode: ParserErrorCode.INVALID_UNICODE_ESCAPE_U_STARTED
   expression:
     - "'\\u'"
+
+InvalidUnicodeEscapeUNoBracket:
+  index: 124
+  problemMessage: "An escape sequence starting with '\\u' must be followed by 4 hexadecimal digits."
+  analyzerCode: ParserErrorCode.INVALID_UNICODE_ESCAPE_U_NO_BRACKET
+  expression:
     - "'\\u0F'"
+
+InvalidUnicodeEscapeUBracket:
+  index: 125
+  problemMessage: "An escape sequence starting with '\\u{' must be followed by 1 to 6 hexadecimal digits followed by a '}'."
+  analyzerCode: ParserErrorCode.INVALID_UNICODE_ESCAPE_U_BRACKET
+  expression:
     - "'\\u{'"
     - "'\\u{03'"
     - "'\\u{0Z}'"
+    - "'\\u{0000003}'"
+
+InvalidEscapeStarted:
+  index: 126
+  problemMessage: "The string '\\' can't stand alone."
+  correctionMessage: "Try adding another backslash (\\) to escape the '\\'."
+  analyzerCode: ParserErrorCode.INVALID_UNICODE_ESCAPE_STARTED
+  exampleAllowMoreCodes: true
+  expression:
+    - |
+      print('Hello, World!\
+      ');
 
 UnexpectedDollarInString:
   problemMessage: "A '$' has special meaning inside a string, and must be followed by an identifier or an expression in curly braces ({})."
diff --git a/pkg/front_end/test/fasta/messages_suite.dart b/pkg/front_end/test/fasta/messages_suite.dart
index df8fbb55cac..6b0ae9ad5dd 100644
--- a/pkg/front_end/test/fasta/messages_suite.dart
+++ b/pkg/front_end/test/fasta/messages_suite.dart
@@ -844,8 +844,11 @@ class Compile extends Step<Example?, Null, MessageTestSuite> {
     }
     return fail(
         null,
-        suite.formatProblems("Too many messages reported in ${example.name}:",
-            example, messages));
+        suite.formatProblems(
+            "Too many or unexpected messages (${messages.length}) reported "
+            "in ${example.name}:",
+            example,
+            messages));
   }
 }
 
diff --git a/pkg/front_end/test/spell_checking_list_code.txt b/pkg/front_end/test/spell_checking_list_code.txt
index 0093dcee802..ac64436f380 100644
--- a/pkg/front_end/test/spell_checking_list_code.txt
+++ b/pkg/front_end/test/spell_checking_list_code.txt
@@ -22,6 +22,7 @@ acon
 acov
 across
 activated
+actively
 adequate
 adi
 advantage
@@ -1363,6 +1364,7 @@ unconditionally
 unconstrained
 undeclare
 undergo
+undermine
 undo
 undoable
 unequal
diff --git a/pkg/front_end/test/spell_checking_list_messages.txt b/pkg/front_end/test/spell_checking_list_messages.txt
index 664608e47db..329dc17c488 100644
--- a/pkg/front_end/test/spell_checking_list_messages.txt
+++ b/pkg/front_end/test/spell_checking_list_messages.txt
@@ -50,6 +50,7 @@ list.filled
 loadlibrary
 macro
 migrate
+n
 name.#name
 name.stack
 nameokempty
@@ -68,11 +69,13 @@ part(s)
 patch(es)
 placing
 pubspec.yaml
+r
 re
 sdksummary
 size
 solutions
 stacktrace
+stand
 staticinterop
 stringokempty
 struct<#name
@@ -80,6 +83,7 @@ structs
 super.namedconstructor
 superinterface
 supermixin
+t
 team
 this.namedconstructor
 this.x
diff --git a/pkg/front_end/testcases/rasta/bad_unicode.dart.weak.expect b/pkg/front_end/testcases/rasta/bad_unicode.dart.weak.expect
index 749bacec393..5c448ec8970 100644
--- a/pkg/front_end/testcases/rasta/bad_unicode.dart.weak.expect
+++ b/pkg/front_end/testcases/rasta/bad_unicode.dart.weak.expect
@@ -2,7 +2,7 @@ library;
 //
 // Problems in library:
 //
-// pkg/front_end/testcases/rasta/bad_unicode.dart:6:10: Error: An escape sequence starting with '\u' must be followed by 4 hexadecimal digits or from 1 to 6 digits between '{' and '}'.
+// pkg/front_end/testcases/rasta/bad_unicode.dart:6:10: Error: An escape sequence starting with '\u' must be followed by 4 hexadecimal digits.
 //   print("\u00"); // Bad Unicode escape, must have 4 hex digits.
 //          ^^^^
 //
diff --git a/pkg/front_end/testcases/rasta/bad_unicode.dart.weak.modular.expect b/pkg/front_end/testcases/rasta/bad_unicode.dart.weak.modular.expect
index 749bacec393..5c448ec8970 100644
--- a/pkg/front_end/testcases/rasta/bad_unicode.dart.weak.modular.expect
+++ b/pkg/front_end/testcases/rasta/bad_unicode.dart.weak.modular.expect
@@ -2,7 +2,7 @@ library;
 //
 // Problems in library:
 //
-// pkg/front_end/testcases/rasta/bad_unicode.dart:6:10: Error: An escape sequence starting with '\u' must be followed by 4 hexadecimal digits or from 1 to 6 digits between '{' and '}'.
+// pkg/front_end/testcases/rasta/bad_unicode.dart:6:10: Error: An escape sequence starting with '\u' must be followed by 4 hexadecimal digits.
 //   print("\u00"); // Bad Unicode escape, must have 4 hex digits.
 //          ^^^^
 //
diff --git a/pkg/front_end/testcases/rasta/bad_unicode.dart.weak.transformed.expect b/pkg/front_end/testcases/rasta/bad_unicode.dart.weak.transformed.expect
index 749bacec393..5c448ec8970 100644
--- a/pkg/front_end/testcases/rasta/bad_unicode.dart.weak.transformed.expect
+++ b/pkg/front_end/testcases/rasta/bad_unicode.dart.weak.transformed.expect
@@ -2,7 +2,7 @@ library;
 //
 // Problems in library:
 //
-// pkg/front_end/testcases/rasta/bad_unicode.dart:6:10: Error: An escape sequence starting with '\u' must be followed by 4 hexadecimal digits or from 1 to 6 digits between '{' and '}'.
+// pkg/front_end/testcases/rasta/bad_unicode.dart:6:10: Error: An escape sequence starting with '\u' must be followed by 4 hexadecimal digits.
 //   print("\u00"); // Bad Unicode escape, must have 4 hex digits.
 //          ^^^^
 //
diff --git a/tests/language/string/escape4_test.dart b/tests/language/string/escape4_test.dart
index 6f4efba9469..0f2a6cbaeb6 100644
--- a/tests/language/string/escape4_test.dart
+++ b/tests/language/string/escape4_test.dart
@@ -9,23 +9,21 @@ main() {
   // static error updater tool, so if you need to tweak the static error
   // expectations in this test, you may need to do so manually.
   print('Hello, World!\
+  //   ^
+  // [cfe] Can't find ')' to match '('.
+  //    ^
+  // [cfe] String starting with ' must end with '.
+  //                  ^
+  // [analyzer] SYNTACTIC_ERROR.INVALID_UNICODE_ESCAPE_STARTED
+  // [analyzer] SYNTACTIC_ERROR.UNTERMINATED_STRING_LITERAL
+  // [cfe] The string '\' can't stand alone.
 ');
-// [error line 11, column 8, length 1]
-// [cfe] Can't find ')' to match '('.
-// [error line 11, column 9, length 1]
-// [cfe] String starting with ' must end with '.
-// [error line 11, column 23, length 1]
-// [analyzer] SYNTACTIC_ERROR.INVALID_UNICODE_ESCAPE
-// [cfe] An escape sequence starting with '\u' must be followed by 4 hexadecimal digits or from 1 to 6 digits between '{' and '}'.
-// [error line 11, column 23, length 1]
-// [analyzer] SYNTACTIC_ERROR.UNTERMINATED_STRING_LITERAL
-// [error line 12, column 1, length 3]
+// [error column 1, length 3]
 // [analyzer] SYNTACTIC_ERROR.EXPECTED_TOKEN
 // [cfe] Expected ';' after this.
-// [error line 12, column 1]
 // [cfe] String starting with ' must end with '.
-// [error line 12, column 3, length 1]
+//^
 // [analyzer] SYNTACTIC_ERROR.UNTERMINATED_STRING_LITERAL
 }
-// [error line 29, column 1, length 1]
+// [error column 1, length 1]
 // [analyzer] SYNTACTIC_ERROR.EXPECTED_TOKEN
diff --git a/tests/language/string/unicode1_test.dart b/tests/language/string/unicode1_test.dart
index 04a9f5f2428..bf87c763040 100644
--- a/tests/language/string/unicode1_test.dart
+++ b/tests/language/string/unicode1_test.dart
@@ -7,10 +7,10 @@
 main() {
   var str = "Foo\u00";
   //            ^^^^
-  // [analyzer] SYNTACTIC_ERROR.INVALID_UNICODE_ESCAPE
-  // [cfe] An escape sequence starting with '\u' must be followed by 4 hexadecimal digits or from 1 to 6 digits between '{' and '}'.
+  // [analyzer] SYNTACTIC_ERROR.INVALID_UNICODE_ESCAPE_U_NO_BRACKET
+  // [cfe] An escape sequence starting with '\u' must be followed by 4 hexadecimal digits.
   str = "Foo\uDEEMBar";
   //        ^^^^^
-  // [analyzer] SYNTACTIC_ERROR.INVALID_UNICODE_ESCAPE
-  // [cfe] An escape sequence starting with '\u' must be followed by 4 hexadecimal digits or from 1 to 6 digits between '{' and '}'.
+  // [analyzer] SYNTACTIC_ERROR.INVALID_UNICODE_ESCAPE_U_NO_BRACKET
+  // [cfe] An escape sequence starting with '\u' must be followed by 4 hexadecimal digits.
 }
diff --git a/tests/language/string/unicode2_test.dart b/tests/language/string/unicode2_test.dart
index 4624fbd33b2..ace2a0feb1d 100644
--- a/tests/language/string/unicode2_test.dart
+++ b/tests/language/string/unicode2_test.dart
@@ -7,11 +7,14 @@
 main() {
   var str = "Foo\u{}Bar";
   //            ^^^^
-  // [analyzer] SYNTACTIC_ERROR.INVALID_UNICODE_ESCAPE
-  // [cfe] An escape sequence starting with '\u' must be followed by 4 hexadecimal digits or from 1 to 6 digits between '{' and '}'.
+  // [analyzer] SYNTACTIC_ERROR.INVALID_UNICODE_ESCAPE_U_BRACKET
+  // [cfe] An escape sequence starting with '\u{' must be followed by 1 to 6 hexadecimal digits followed by a '}'.
   str = "Foo\u{000000000}Bar";
+  //        ^^^^^^^^^
+  // [analyzer] SYNTACTIC_ERROR.INVALID_UNICODE_ESCAPE_U_BRACKET
+  // [cfe] An escape sequence starting with '\u{' must be followed by 1 to 6 hexadecimal digits followed by a '}'.
   str = "Foo\u{DEAF!}Bar";
   //        ^^^^^^^^
-  // [analyzer] SYNTACTIC_ERROR.INVALID_UNICODE_ESCAPE
-  // [cfe] An escape sequence starting with '\u' must be followed by 4 hexadecimal digits or from 1 to 6 digits between '{' and '}'.
+  // [analyzer] SYNTACTIC_ERROR.INVALID_UNICODE_ESCAPE_U_BRACKET
+  // [cfe] An escape sequence starting with '\u{' must be followed by 1 to 6 hexadecimal digits followed by a '}'.
 }
diff --git a/tests/language_2/string/escape4_test.dart b/tests/language_2/string/escape4_test.dart
index fb83da25063..cfedc5d26ee 100644
--- a/tests/language_2/string/escape4_test.dart
+++ b/tests/language_2/string/escape4_test.dart
@@ -11,23 +11,21 @@ main() {
   // static error updater tool, so if you need to tweak the static error
   // expectations in this test, you may need to do so manually.
   print('Hello, World!\
+  //   ^
+  // [cfe] Can't find ')' to match '('.
+  //    ^
+  // [cfe] String starting with ' must end with '.
+  //                  ^
+  // [analyzer] SYNTACTIC_ERROR.INVALID_UNICODE_ESCAPE_STARTED
+  // [analyzer] SYNTACTIC_ERROR.UNTERMINATED_STRING_LITERAL
+  // [cfe] The string '\' can't stand alone.
 ');
-// [error line 13, column 8, length 1]
-// [cfe] Can't find ')' to match '('.
-// [error line 13, column 9, length 1]
-// [cfe] String starting with ' must end with '.
-// [error line 13, column 23, length 1]
-// [analyzer] SYNTACTIC_ERROR.INVALID_UNICODE_ESCAPE
-// [cfe] An escape sequence starting with '\u' must be followed by 4 hexadecimal digits or from 1 to 6 digits between '{' and '}'.
-// [error line 13, column 23, length 1]
-// [analyzer] SYNTACTIC_ERROR.UNTERMINATED_STRING_LITERAL
-// [error line 14, column 1, length 3]
+// [error column 1, length 3]
 // [analyzer] SYNTACTIC_ERROR.EXPECTED_TOKEN
 // [cfe] Expected ';' after this.
-// [error line 14, column 1]
 // [cfe] String starting with ' must end with '.
-// [error line 14, column 3, length 1]
+//^
 // [analyzer] SYNTACTIC_ERROR.UNTERMINATED_STRING_LITERAL
 }
-// [error line 31, column 1, length 1]
+// [error column 1, length 1]
 // [analyzer] SYNTACTIC_ERROR.EXPECTED_TOKEN
diff --git a/tests/language_2/string/unicode1_test.dart b/tests/language_2/string/unicode1_test.dart
index 58b39bdc305..78443308648 100644
--- a/tests/language_2/string/unicode1_test.dart
+++ b/tests/language_2/string/unicode1_test.dart
@@ -9,10 +9,10 @@
 main() {
   var str = "Foo\u00";
   //            ^^^^
-  // [analyzer] SYNTACTIC_ERROR.INVALID_UNICODE_ESCAPE
-  // [cfe] An escape sequence starting with '\u' must be followed by 4 hexadecimal digits or from 1 to 6 digits between '{' and '}'.
+  // [analyzer] SYNTACTIC_ERROR.INVALID_UNICODE_ESCAPE_U_NO_BRACKET
+  // [cfe] An escape sequence starting with '\u' must be followed by 4 hexadecimal digits.
   str = "Foo\uDEEMBar";
   //        ^^^^^
-  // [analyzer] SYNTACTIC_ERROR.INVALID_UNICODE_ESCAPE
-  // [cfe] An escape sequence starting with '\u' must be followed by 4 hexadecimal digits or from 1 to 6 digits between '{' and '}'.
+  // [analyzer] SYNTACTIC_ERROR.INVALID_UNICODE_ESCAPE_U_NO_BRACKET
+  // [cfe] An escape sequence starting with '\u' must be followed by 4 hexadecimal digits.
 }
diff --git a/tests/language_2/string/unicode2_test.dart b/tests/language_2/string/unicode2_test.dart
index 042b64209cd..6c2cb90e099 100644
--- a/tests/language_2/string/unicode2_test.dart
+++ b/tests/language_2/string/unicode2_test.dart
@@ -9,11 +9,14 @@
 main() {
   var str = "Foo\u{}Bar";
   //            ^^^^
-  // [analyzer] SYNTACTIC_ERROR.INVALID_UNICODE_ESCAPE
-  // [cfe] An escape sequence starting with '\u' must be followed by 4 hexadecimal digits or from 1 to 6 digits between '{' and '}'.
+  // [analyzer] SYNTACTIC_ERROR.INVALID_UNICODE_ESCAPE_U_BRACKET
+  // [cfe] An escape sequence starting with '\u{' must be followed by 1 to 6 hexadecimal digits followed by a '}'.
   str = "Foo\u{000000000}Bar";
+  //        ^^^^^^^^^
+  // [analyzer] SYNTACTIC_ERROR.INVALID_UNICODE_ESCAPE_U_BRACKET
+  // [cfe] An escape sequence starting with '\u{' must be followed by 1 to 6 hexadecimal digits followed by a '}'.
   str = "Foo\u{DEAF!}Bar";
   //        ^^^^^^^^
-  // [analyzer] SYNTACTIC_ERROR.INVALID_UNICODE_ESCAPE
-  // [cfe] An escape sequence starting with '\u' must be followed by 4 hexadecimal digits or from 1 to 6 digits between '{' and '}'.
+  // [analyzer] SYNTACTIC_ERROR.INVALID_UNICODE_ESCAPE_U_BRACKET
+  // [cfe] An escape sequence starting with '\u{' must be followed by 1 to 6 hexadecimal digits followed by a '}'.
 }