diff --git a/tests/phpt/dl/482_ob.php b/tests/phpt/dl/482_ob.php
index c2efd9b99e..d44fb10271 100644
--- a/tests/phpt/dl/482_ob.php
+++ b/tests/phpt/dl/482_ob.php
@@ -1,9 +1,14 @@
-@ok k2_skip
+@ok
 <?php
   ob_start();
   echo "1:blah\n";
   ob_start();
-  echo "2:blah";
+  echo "2:blah\n";
+  ob_start();
+  echo "3:blah\n";
+  ob_clean();
+  var_dump(ob_get_clean());
+  var_dump("0");
   var_dump(ob_get_clean());
   var_dump("0");
   var_dump(ob_get_clean());
diff --git a/tests/phpt/dl/495_sort.php b/tests/phpt/dl/495_sort.php
index 040b8cd398..e61a35c07e 100644
--- a/tests/phpt/dl/495_sort.php
+++ b/tests/phpt/dl/495_sort.php
@@ -44,6 +44,8 @@ function cmp ($a, $b) {
   $to_sort[rand(0, 1000000000)] = rand(0, 1000000000);
 }
 
+shuffle ($to_sort);
+
 asort ($to_sort);
 
 krsort ($to_sort);
diff --git a/tests/python/tests/diagnostic/php/index.php b/tests/python/tests/diagnostic/php/index.php
index e72f8ec830..dd7597ff1f 100644
--- a/tests/python/tests/diagnostic/php/index.php
+++ b/tests/python/tests/diagnostic/php/index.php
@@ -76,7 +76,7 @@ function forkable() {
     return wait($f);
 }
 
-function main() {
+function test_backtrace() {
     foreach (json_decode(file_get_contents('php://input')) as $action) {
         switch ($action["op"]) {
             case "check_main_trace":
@@ -109,5 +109,61 @@ function main() {
     }
 }
 
+function make_custom_exception() {
+    return err('TEST', 'London is the capital of Great Britain');
+}
+
+function check_exception(Exception $e) {
+    if ($e->getFile() != 'index.php')
+        return 'expected "index.php" but "' . $e->getFile() . '" found';
+
+    if ($e->getLine() != 113)
+        return 'expected 113 but ' . $e->getLine() . ' found';
+
+    if ($e->getCode() != 0)
+        return 'expected 0 but ' . $e->getCode() . ' found';
+
+    if ($e->getMessage() != 'ERR_TEST: London is the capital of Great Britain')
+        return 'expected "ERR_TEST: London is the capital of Great Britain" but "' . $e->getMessage() . '" found';
+
+    return 'ok';
+}
+
+function test_err() {
+    foreach (json_decode(file_get_contents('php://input')) as $action) {
+        switch ($action["op"]) {
+            case "just_make":
+                $e = make_custom_exception();
+                $res = check_exception($e);
+                echo $res;
+                break;
+            case "throw_catch":
+                try {
+                    throw make_custom_exception();
+                } catch (Exception $e) {
+                    $res = check_exception($e);
+                }
+                echo $res;
+                break;
+            default:
+                echo "unknown operation";
+                return;
+        }
+    }
+}
+
+function main() {
+    switch ($_SERVER["PHP_SELF"]) {
+        case "/test_backtrace":
+            test_backtrace();
+            break;
+        case "/test_err":
+            test_err();
+            break;
+        default:
+            critical_error("unknown test");
+    }
+}
+
 main();
 
diff --git a/tests/python/tests/diagnostic/test_backtrace.py b/tests/python/tests/diagnostic/test_backtrace.py
index d4dda2ab49..ced6026c2c 100644
--- a/tests/python/tests/diagnostic/test_backtrace.py
+++ b/tests/python/tests/diagnostic/test_backtrace.py
@@ -6,35 +6,20 @@ class TestBacktrace(WebServerAutoTestCase):
     @classmethod
     def extra_kphp2cpp_options(cls):
         return {"KPHP_EXTRA_CXXFLAGS" : "-O0 -g"}
-
-    def test_main_fork_trace(self):
-        resp = self.web_server.http_post(
-            json=[
-                {"op": "check_main_trace"},
-            ])
+    
+    def query(self, op: str):
+        resp = self.web_server.http_post(uri="/test_backtrace", json=[{"op": op}])
         self.assertEqual(resp.text, "ok")
         self.assertEqual(resp.status_code, 200)
 
+    def test_main_fork_trace(self):
+        self.query("check_main_trace")
+
     def test_fork_trace(self):
-        resp = self.web_server.http_post(
-            json=[
-                {"op": "check_fork_trace"},
-            ])
-        self.assertEqual(resp.text, "ok")
-        self.assertEqual(resp.status_code, 200)
+        self.query("check_fork_trace")
 
     def test_fork_switch_trace(self):
-        resp = self.web_server.http_post(
-            json=[
-                {"op": "check_fork_switch_trace"},
-            ])
-        self.assertEqual(resp.text, "ok")
-        self.assertEqual(resp.status_code, 200)
+        self.query("check_fork_switch_trace")
 
     def test_nested_fork_trace(self):
-        resp = self.web_server.http_post(
-            json=[
-                {"op": "check_nested_fork_trace"},
-            ])
-        self.assertEqual(resp.text, "ok")
-        self.assertEqual(resp.status_code, 200)
+        self.query("check_nested_fork_trace")
diff --git a/tests/python/tests/diagnostic/test_err.py b/tests/python/tests/diagnostic/test_err.py
new file mode 100644
index 0000000000..05a3c9ab69
--- /dev/null
+++ b/tests/python/tests/diagnostic/test_err.py
@@ -0,0 +1,15 @@
+import pytest
+from python.lib.testcase import WebServerAutoTestCase
+
+
+class TestErr(WebServerAutoTestCase):
+    def query(self, op: str):
+        resp = self.web_server.http_post(uri="/test_err", json=[{"op": op}])
+        self.assertEqual(resp.text, "ok")
+        self.assertEqual(resp.status_code, 200)
+
+    def test_just_make(self):
+        self.query("just_make")
+
+    def test_throw_catch(self):
+        self.query("throw_catch")