diff --git a/ets2panda/compiler/lowering/ets/defaultParametersInConstructorLowering.cpp b/ets2panda/compiler/lowering/ets/defaultParametersInConstructorLowering.cpp
index 3b7466ef9f897a990ee8dd8fc993079a97ad7dc7..61e62947c6dbe331b77f01b099267e94104b861d 100644
--- a/ets2panda/compiler/lowering/ets/defaultParametersInConstructorLowering.cpp
+++ b/ets2panda/compiler/lowering/ets/defaultParametersInConstructorLowering.cpp
@@ -35,8 +35,11 @@ static bool HasDefaultParameters(const ir::ScriptFunction *function, util::Diagn
         }
 
         if (hasRestParameter) {
-            util::DiagnosticMessageParams diagnosticParams = {};
-            diagnosticEngine.LogDiagnostic(diagnostic::REST_PARAM_LAST, std::move(diagnosticParams), param->Start());
+            // NOTE(pronai): This seems to be covered in parser. As the comment above says, it's unclear why the
+            // lowering is needed.
+            ES2PANDA_UNREACHABLE_POS(param->Start());
+            diagnosticEngine.LogDiagnostic(diagnostic::REST_PARAM_NOT_LAST, util::DiagnosticMessageParams {},
+                                           param->Start());
         }
 
         if (param->IsOptional()) {
diff --git a/ets2panda/test/ast/parser/ets/default_parameter3.ets b/ets2panda/test/ast/parser/ets/default_parameter3.ets
index a1ea174314af3add6e8317a2595810cc60eeafa6..80c76508f8a0a8e3b18f3bd1bc9ff341ff6df977 100644
--- a/ets2panda/test/ast/parser/ets/default_parameter3.ets
+++ b/ets2panda/test/ast/parser/ets/default_parameter3.ets
@@ -18,4 +18,4 @@ function foo(a : int = 10, /* @@ label */b : int, c : int = 15) : int
     return a + b;
 }
 
-/* @@@ label Error SyntaxError: Required parameter follows default parameter(s).  */
+/* @@@ label Error SyntaxError: A required parameter cannot follow an optional parameter. */
diff --git a/ets2panda/test/ast/parser/ets/nolint_bad.ets b/ets2panda/test/ast/parser/ets/nolint_bad.ets
new file mode 100644
index 0000000000000000000000000000000000000000..b4aa54d09744e878c4403a61fc3792f11e0aa11d
--- /dev/null
+++ b/ets2panda/test/ast/parser/ets/nolint_bad.ets
@@ -0,0 +1,22 @@
+/*
+ * Copyright (c) 2025 Huawei Device Co., Ltd.
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+
+// ETSNOLINT(definitely-not-a-real-etsnolint-argument)
+// ETSNOLINT(@)
+function main() {}
+/* @@? 1:3 Error SyntaxError: Invalid argument for ETSNOLINT! */
+/* @@? 1:3 Error SyntaxError: Unexpected character for ETSNOLINT argument! [VALID ONLY: a-z, '-']. */
+/* @@? 1:3 Error SyntaxError: Invalid argument for ETSNOLINT! */
diff --git a/ets2panda/test/ast/parser/js/private_ctor_bad.js b/ets2panda/test/ast/parser/js/private_ctor_bad.js
new file mode 100644
index 0000000000000000000000000000000000000000..1b9477045f2682176e219e5d18c7db2125030c6d
--- /dev/null
+++ b/ets2panda/test/ast/parser/js/private_ctor_bad.js
@@ -0,0 +1,20 @@
+/*
+ * Copyright (c) 2025 Huawei Device Co., Ltd.
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+
+class A {
+    #constructor(){}
+}
+/* @@? 18:6 Error SyntaxError: Private identifier can not be constructor. */
diff --git a/ets2panda/test/ast/parser/js/private_number_bad.js b/ets2panda/test/ast/parser/js/private_number_bad.js
new file mode 100644
index 0000000000000000000000000000000000000000..94cd82cad0adec7fc72ee2b4572247a0019ed93a
--- /dev/null
+++ b/ets2panda/test/ast/parser/js/private_number_bad.js
@@ -0,0 +1,20 @@
+/*
+ * Copyright (c) 2025 Huawei Device Co., Ltd.
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+class WeAre {
+    #1
+}
+/* @@? 17:6 Error SyntaxError: Unexpected token in private field. */
+/* @@? 17:6 Error SyntaxError: Private identifier name can not be number. */
diff --git a/ets2panda/test/ast/parser/js/private_ref_bad.js b/ets2panda/test/ast/parser/js/private_ref_bad.js
new file mode 100644
index 0000000000000000000000000000000000000000..cc4b234705d69a92b2be25ca18a4cc86fb8deede
--- /dev/null
+++ b/ets2panda/test/ast/parser/js/private_ref_bad.js
@@ -0,0 +1,21 @@
+/*
+ * Copyright (c) 2025 Huawei Device Co., Ltd.
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+class A{
+    m(){
+        return this.#x
+    }
+}
+/* @@? 18:21 Error SyntaxError: Private field 'x' must be declared in an enclosing class */
diff --git a/ets2panda/test/ast/parser/js/private_sqbracket_bad.js b/ets2panda/test/ast/parser/js/private_sqbracket_bad.js
new file mode 100644
index 0000000000000000000000000000000000000000..426ccec09f494b4ac77389b6317cfa181521c25e
--- /dev/null
+++ b/ets2panda/test/ast/parser/js/private_sqbracket_bad.js
@@ -0,0 +1,23 @@
+/*
+ * Copyright (c) 2025 Huawei Device Co., Ltd.
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+class WeAre {
+    #[
+}
+/* @@? 17:6 Error SyntaxError: Unexpected token in private field. */
+/* @@? 17:6 Error SyntaxError: Unexpected character in private identifier. */
+/* @@? 18:1 Error SyntaxError: Unexpected token '}'. */
+/* @@? 18:1 Error SyntaxError: Unexpected token, expected ']'. */
+/* @@? 24:1 Error SyntaxError: Expected '}', got 'end of stream'. */
diff --git a/ets2panda/test/ast/parser/js/private_string_bad.js b/ets2panda/test/ast/parser/js/private_string_bad.js
new file mode 100644
index 0000000000000000000000000000000000000000..58c411b6fd9fcc16fd4c6cbaa533c681c3b85836
--- /dev/null
+++ b/ets2panda/test/ast/parser/js/private_string_bad.js
@@ -0,0 +1,20 @@
+/*
+ * Copyright (c) 2025 Huawei Device Co., Ltd.
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+class WeAre {
+    #"one"
+}
+/* @@? 17:6 Error SyntaxError: Unexpected token in private field. */
+/* @@? 17:6 Error SyntaxError: Private identifier name can not be string. */
diff --git a/ets2panda/test/test-lists/astchecker/astchecker-ets-ignored.txt b/ets2panda/test/test-lists/astchecker/astchecker-ets-ignored.txt
index f6ce7f89771847e79cca31e8d503afcabd7e9957..857f45c9f14fef63bfe2fb392c13dde024a6aff2 100644
--- a/ets2panda/test/test-lists/astchecker/astchecker-ets-ignored.txt
+++ b/ets2panda/test/test-lists/astchecker/astchecker-ets-ignored.txt
@@ -77,7 +77,6 @@ ast/compiler/ets/readonlyType_5.ets
 ast/parser/ets/InferTypeParamFromParam2.ets
 
 # Issue: #23080
-ast/parser/ets/default_parameter3.ets
 ast/parser/ets/default_parameters_multi_error.ets
 ast/parser/ets/rest_parameter_03.ets
 
diff --git a/ets2panda/util/diagnostic/syntax.yaml b/ets2panda/util/diagnostic/syntax.yaml
index 9a9440342d68c36cb550610b74158cd609639d22..17be683a79678cebc0e27690a1628748332a485c 100644
--- a/ets2panda/util/diagnostic/syntax.yaml
+++ b/ets2panda/util/diagnostic/syntax.yaml
@@ -398,10 +398,6 @@ syntax:
   id: 172
   message: "Illegal newline after throw."
 
-- name: ILLEGAL_START_EXPRESSION
-  id: 208
-  message: "Illegal start of expression."
-
 - name: ILLEGAL_START_STRUCT_CLASS
   id: 40
   message: "Illegal start of {} expression."
@@ -459,10 +455,6 @@ syntax:
   id: 18
   message: "Index type must be number in index signature."
 
-- name: INITIALIZERS_INTERFACE_PROPS
-  id: 123
-  message: "Initializers are not allowed on interface properties."
-
 - name: INITIALIZERS_IN_AMBIENT_CONTEXTS
   id: 125
   message: "Initializers are not allowed in ambient contexts."
@@ -822,10 +814,6 @@ syntax:
   id: 73
   message: "'new.Target' is not allowed here."
 
-- name: NEW_TARGET_WITH_ESCAPED_CHARS
-  id: 74
-  message: "'new.Target' must not contain escaped characters."
-
 - name: NEW_WITH_IMPORT
   id: 60
   message: "Cannot use new with import(...)."
@@ -878,10 +866,6 @@ syntax:
   id: 321
   message: "initModule() only accept string literal as argument."
 
-- name: ONLY_THROWS_IN_FUN_TYPE
-  id: 103
-  message: "Only 'throws' can be used with function types."
-
 - name: OPTIONAL_VARIABLE
   id: 306
   message: "Optional variable is deprecated and no longer supported."
@@ -990,10 +974,6 @@ syntax:
   id: 15
   message: "Both optional and rest parameters are not allowed in function's parameter list."
 
-- name: REST_PARAM_LAST
-  id: 236
-  message: "Rest parameter should be the last one."
-
 - name: REST_PARAM_NOT_LAST
   id: 67
   message: "Rest parameter must be the last formal parameter."
@@ -1271,13 +1251,18 @@ graveyard:
 - 29
 - 37
 - 41
+- 74
+- 103
 - 109
+- 123
 - 139
 - 142
 - 152
 - 157
+- 208
 - 218
 - 235
+- 236
 - 272
 - 274
 - 275