diff --git a/src/Control/PjaxResponseNegotiator.php b/src/Control/PjaxResponseNegotiator.php
index 53557a7ea..e87d104e2 100644
--- a/src/Control/PjaxResponseNegotiator.php
+++ b/src/Control/PjaxResponseNegotiator.php
@@ -102,7 +102,7 @@ class PjaxResponseNegotiator
                 throw new HTTPResponse_Exception("X-Pjax = '$fragment' not supported for this URL.", 400);
             }
         }
-        $response->setBody(Convert::raw2json($responseParts));
+        $response->setBody(json_encode($responseParts));
         $response->addHeader('Content-Type', 'application/json');
 
         return $response;
diff --git a/src/Core/Manifest/VersionProvider.php b/src/Core/Manifest/VersionProvider.php
index c2f307931..fee190057 100644
--- a/src/Core/Manifest/VersionProvider.php
+++ b/src/Core/Manifest/VersionProvider.php
@@ -95,12 +95,12 @@ class VersionProvider
             $cache = Injector::inst()->get(CacheInterface::class . '.VersionProvider_composerlock');
             $cacheKey = md5($jsonData);
             if ($versions = $cache->get($cacheKey)) {
-                $lockData = Convert::json2array($versions);
+                $lockData = json_decode($versions, true);
             }
         }
 
         if (empty($lockData) && $jsonData) {
-            $lockData = Convert::json2array($jsonData);
+            $lockData = json_decode($jsonData, true);
 
             if ($cache) {
                 $cache->set($cacheKey, $jsonData);
diff --git a/src/Forms/FormRequestHandler.php b/src/Forms/FormRequestHandler.php
index 4392ab3bc..835b0762c 100644
--- a/src/Forms/FormRequestHandler.php
+++ b/src/Forms/FormRequestHandler.php
@@ -376,7 +376,7 @@ class FormRequestHandler extends RequestHandler
         $acceptType = $this->getRequest()->getHeader('Accept');
         if (strpos($acceptType, 'application/json') !== false) {
             // Send validation errors back as JSON with a flag at the start
-            $response = new HTTPResponse(Convert::array2json($result->getMessages()));
+            $response = new HTTPResponse(json_encode($result->getMessages()));
             $response->addHeader('Content-Type', 'application/json');
             return $response;
         }
diff --git a/src/Forms/GridField/GridFieldAddExistingAutocompleter.php b/src/Forms/GridField/GridFieldAddExistingAutocompleter.php
index 48a45a945..290cdb749 100644
--- a/src/Forms/GridField/GridFieldAddExistingAutocompleter.php
+++ b/src/Forms/GridField/GridFieldAddExistingAutocompleter.php
@@ -262,7 +262,7 @@ class GridFieldAddExistingAutocompleter implements GridField_HTMLProvider, GridF
             );
         }
         Config::unnest();
-        $response = new HTTPResponse(Convert::array2json($json));
+        $response = new HTTPResponse(json_encode($json));
         $response->addHeader('Content-Type', 'application/json');
         return $response;
     }
diff --git a/src/Forms/GridField/GridFieldFilterHeader.php b/src/Forms/GridField/GridFieldFilterHeader.php
index fd3dd8ea9..802340d78 100755
--- a/src/Forms/GridField/GridFieldFilterHeader.php
+++ b/src/Forms/GridField/GridFieldFilterHeader.php
@@ -291,7 +291,7 @@ class GridFieldFilterHeader implements GridField_URLHandler, GridField_HTMLProvi
             'clearAction' => GridField_FormAction::create($gridField, 'reset', false, 'reset', null)->getAttribute('name')
         ];
 
-        return Convert::raw2json($schema);
+        return json_encode($schema);
     }
 
     /**
@@ -377,7 +377,7 @@ class GridFieldFilterHeader implements GridField_URLHandler, GridField_HTMLProvi
         $data = FormSchema::singleton()
             ->getMultipartSchema($parts, $schemaID, $form);
 
-        $response = new HTTPResponse(Convert::raw2json($data));
+        $response = new HTTPResponse(json_encode($data));
         $response->addHeader('Content-Type', 'application/json');
         return $response;
     }
diff --git a/src/Forms/GridField/GridField_ActionMenu.php b/src/Forms/GridField/GridField_ActionMenu.php
index 1dfff1a6d..351f38a3d 100644
--- a/src/Forms/GridField/GridField_ActionMenu.php
+++ b/src/Forms/GridField/GridField_ActionMenu.php
@@ -48,7 +48,7 @@ class GridField_ActionMenu implements GridField_ColumnProvider, GridField_Action
         }
 
         $templateData = ArrayData::create([
-            'Schema' => Convert::raw2json($schema),
+            'Schema' => json_encode($schema),
         ]);
 
         $template = SSViewer::get_templates_by_class($this, '', static::class);
diff --git a/src/Forms/HTMLEditor/TinyMCEConfig.php b/src/Forms/HTMLEditor/TinyMCEConfig.php
index 9dbeb3ceb..06314e750 100644
--- a/src/Forms/HTMLEditor/TinyMCEConfig.php
+++ b/src/Forms/HTMLEditor/TinyMCEConfig.php
@@ -371,7 +371,7 @@ class TinyMCEConfig extends HTMLEditorConfig
     {
         return [
             'data-editor' => 'tinyMCE', // Register ss.editorWrappers.tinyMCE
-            'data-config' => Convert::array2json($this->getConfig()),
+            'data-config' => json_encode($this->getConfig()),
         ];
     }
 
diff --git a/src/ORM/FieldType/DBField.php b/src/ORM/FieldType/DBField.php
index 70aa13cb4..20be1e08d 100644
--- a/src/ORM/FieldType/DBField.php
+++ b/src/ORM/FieldType/DBField.php
@@ -487,7 +487,7 @@ abstract class DBField extends ViewableData implements DBIndexable
      */
     public function JSON()
     {
-        return Convert::raw2json($this->RAW());
+        return json_encode($this->RAW());
     }
 
     /**
diff --git a/tests/php/Forms/GridField/GridFieldAddExistingAutocompleterTest.php b/tests/php/Forms/GridField/GridFieldAddExistingAutocompleterTest.php
index b5a017845..2a427700a 100644
--- a/tests/php/Forms/GridField/GridFieldAddExistingAutocompleterTest.php
+++ b/tests/php/Forms/GridField/GridFieldAddExistingAutocompleterTest.php
@@ -64,7 +64,7 @@ class GridFieldAddExistingAutocompleterTest extends FunctionalTest
             array((string)$btns[0]['name'] => 1)
         );
         $this->assertFalse($response->isError());
-        $result = Convert::json2array($response->getBody());
+        $result = json_decode($response->getBody(), true);
         $this->assertEquals(1, count($result));
         $this->assertEquals(
             array(array(
@@ -81,7 +81,7 @@ class GridFieldAddExistingAutocompleterTest extends FunctionalTest
             array((string)$btns[0]['name'] => 1)
         );
         $this->assertFalse($response->isError());
-        $result = Convert::json2array($response->getBody());
+        $result = json_decode($response->getBody(), true);
         $this->assertEquals(1, count($result), "The relational filter did not work");
 
         $response = $this->post(
@@ -90,7 +90,7 @@ class GridFieldAddExistingAutocompleterTest extends FunctionalTest
             array((string)$btns[0]['name'] => 1)
         );
         $this->assertFalse($response->isError());
-        $result = Convert::json2array($response->getBody());
+        $result = json_decode($response->getBody(), true);
         $this->assertEmpty($result, 'The output is either an empty array or boolean FALSE');
     }
 
diff --git a/tests/php/Forms/HTMLEditor/HTMLEditorConfigTest.php b/tests/php/Forms/HTMLEditor/HTMLEditorConfigTest.php
index da665a96f..8b1fa62f5 100644
--- a/tests/php/Forms/HTMLEditor/HTMLEditorConfigTest.php
+++ b/tests/php/Forms/HTMLEditor/HTMLEditorConfigTest.php
@@ -69,7 +69,7 @@ class HTMLEditorConfigTest extends SapphireTest
             )
         );
         $attributes = $c->getAttributes();
-        $config = Convert::json2array($attributes['data-config']);
+        $config = json_decode($attributes['data-config'], true);
         $plugins = $config['external_plugins'];
         $this->assertNotEmpty($plugins);