diff --git a/composer.json b/composer.json
index 9140ef0ba652bee29afb9442525894584480a4cb..a6251b07877d14de8c8f4730f4286b73c06a0a9c 100644
--- a/composer.json
+++ b/composer.json
@@ -27,8 +27,8 @@
         "phpunit/phpunit": "^8.5.14 || ^9",
         "phpspec/prophecy": "^1.12",
         "symfony/css-selector": "^4.4",
-        "symfony/phpunit-bridge": "^5.1.4",
-        "symfony/var-dumper": "^5.1.2",
+        "symfony/phpunit-bridge": "^5.3.0-rc1",
+        "symfony/var-dumper": "^5.3.0-rc1",
         "symfony/error-handler": "^4.4",
         "justinrainbow/json-schema": "^5.2",
         "symfony/filesystem": "^4.4",
diff --git a/composer.lock b/composer.lock
index 6ddd74174b5ad23234ff6da83317d25c433e9d55..a0557a0147e229f4f9d8612d4436d8ed4ec4523d 100644
--- a/composer.lock
+++ b/composer.lock
@@ -4,7 +4,7 @@
         "Read more about it at https://getcomposer.org/doc/01-basic-usage.md#installing-dependencies",
         "This file is @generated automatically"
     ],
-    "content-hash": "a21f5caf56f7a0d3a198f41c3fb84eac",
+    "content-hash": "9caab8f13f1024c45a4184d7c351370c",
     "packages": [
         {
             "name": "asm89/stack-cors",
@@ -534,7 +534,7 @@
             "dist": {
                 "type": "path",
                 "url": "core",
-                "reference": "8c4a55a02c2380b587e1d59919848c0305c237ff"
+                "reference": "454ec5a15af2123c790974d1ad622bbb8ed61ec5"
             },
             "require": {
                 "asm89/stack-cors": "^1.1",
@@ -569,7 +569,7 @@
                 "symfony/event-dispatcher": "^4.4",
                 "symfony/http-foundation": "^4.4.7",
                 "symfony/http-kernel": "^4.4",
-                "symfony/mime": "^5.2",
+                "symfony/mime": "^5.3.0-rc1",
                 "symfony/polyfill-iconv": "^1.0",
                 "symfony/process": "^4.4",
                 "symfony/psr-http-message-bridge": "^2.0",
@@ -2996,16 +2996,16 @@
         },
         {
             "name": "symfony/mime",
-            "version": "v5.2.9",
+            "version": "v5.3.0-RC1",
             "source": {
                 "type": "git",
                 "url": "https://github.com/symfony/mime.git",
-                "reference": "64258e870f8cc75c3dae986201ea2df58c210b52"
+                "reference": "0c3daded809edda4adee7179122a2a98069d8df7"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/symfony/mime/zipball/64258e870f8cc75c3dae986201ea2df58c210b52",
-                "reference": "64258e870f8cc75c3dae986201ea2df58c210b52",
+                "url": "https://api.github.com/repos/symfony/mime/zipball/0c3daded809edda4adee7179122a2a98069d8df7",
+                "reference": "0c3daded809edda4adee7179122a2a98069d8df7",
                 "shasum": ""
             },
             "require": {
@@ -3059,7 +3059,7 @@
                 "mime-type"
             ],
             "support": {
-                "source": "https://github.com/symfony/mime/tree/v5.2.9"
+                "source": "https://github.com/symfony/mime/tree/v5.3.0-RC1"
             },
             "funding": [
                 {
@@ -3075,7 +3075,7 @@
                     "type": "tidelift"
                 }
             ],
-            "time": "2021-05-16T13:07:46+00:00"
+            "time": "2021-05-16T13:08:56+00:00"
         },
         {
             "name": "symfony/polyfill-ctype",
@@ -4252,16 +4252,16 @@
         },
         {
             "name": "symfony/var-dumper",
-            "version": "v5.2.8",
+            "version": "v5.3.0-RC1",
             "source": {
                 "type": "git",
                 "url": "https://github.com/symfony/var-dumper.git",
-                "reference": "d693200a73fae179d27f8f1b16b4faf3e8569eba"
+                "reference": "29988c9bcac7bb66a03f00a2adaae131778db61c"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/symfony/var-dumper/zipball/d693200a73fae179d27f8f1b16b4faf3e8569eba",
-                "reference": "d693200a73fae179d27f8f1b16b4faf3e8569eba",
+                "url": "https://api.github.com/repos/symfony/var-dumper/zipball/29988c9bcac7bb66a03f00a2adaae131778db61c",
+                "reference": "29988c9bcac7bb66a03f00a2adaae131778db61c",
                 "shasum": ""
             },
             "require": {
@@ -4320,7 +4320,7 @@
                 "dump"
             ],
             "support": {
-                "source": "https://github.com/symfony/var-dumper/tree/v5.2.8"
+                "source": "https://github.com/symfony/var-dumper/tree/v5.3.0-RC1"
             },
             "funding": [
                 {
@@ -4336,7 +4336,7 @@
                     "type": "tidelift"
                 }
             ],
-            "time": "2021-05-07T13:42:21+00:00"
+            "time": "2021-05-07T14:34:05+00:00"
         },
         {
             "name": "symfony/yaml",
@@ -7810,26 +7810,26 @@
         },
         {
             "name": "symfony/phpunit-bridge",
-            "version": "v5.2.9",
+            "version": "v5.3.0-RC1",
             "source": {
                 "type": "git",
                 "url": "https://github.com/symfony/phpunit-bridge.git",
-                "reference": "ea24e42c1ee04792f5d814da6f0814b20ece2907"
+                "reference": "f2ecbe9ce01a91dac62356560f1cc903ab689de0"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/symfony/phpunit-bridge/zipball/ea24e42c1ee04792f5d814da6f0814b20ece2907",
-                "reference": "ea24e42c1ee04792f5d814da6f0814b20ece2907",
+                "url": "https://api.github.com/repos/symfony/phpunit-bridge/zipball/f2ecbe9ce01a91dac62356560f1cc903ab689de0",
+                "reference": "f2ecbe9ce01a91dac62356560f1cc903ab689de0",
                 "shasum": ""
             },
             "require": {
-                "php": ">=5.5.9"
+                "php": ">=7.1.3",
+                "symfony/deprecation-contracts": "^2.1"
             },
             "conflict": {
-                "phpunit/phpunit": "<4.8.35|<5.4.3,>=5.0|<6.4,>=6.0|9.1.2"
+                "phpunit/phpunit": "<7.5|9.1.2"
             },
             "require-dev": {
-                "symfony/deprecation-contracts": "^2.1",
                 "symfony/error-handler": "^4.4|^5.0"
             },
             "suggest": {
@@ -7873,7 +7873,7 @@
             "description": "Provides utilities for PHPUnit, especially user deprecation notices management",
             "homepage": "https://symfony.com",
             "support": {
-                "source": "https://github.com/symfony/phpunit-bridge/tree/v5.2.9"
+                "source": "https://github.com/symfony/phpunit-bridge/tree/v5.3.0-RC1"
             },
             "funding": [
                 {
@@ -7889,7 +7889,7 @@
                     "type": "tidelift"
                 }
             ],
-            "time": "2021-05-16T13:07:46+00:00"
+            "time": "2021-05-16T13:08:56+00:00"
         },
         {
             "name": "theseer/tokenizer",
diff --git a/composer/Metapackage/CoreRecommended/composer.json b/composer/Metapackage/CoreRecommended/composer.json
index b9c77d17fbc74b5973ba0b5f1112e7149d6a4973..e5dbaa32070871eccaef4b941809506caea3c935 100644
--- a/composer/Metapackage/CoreRecommended/composer.json
+++ b/composer/Metapackage/CoreRecommended/composer.json
@@ -45,7 +45,7 @@
         "symfony/http-client-contracts": "v2.4.0",
         "symfony/http-foundation": "v4.4.23",
         "symfony/http-kernel": "v4.4.24",
-        "symfony/mime": "v5.2.9",
+        "symfony/mime": "v5.3.0-RC1",
         "symfony/polyfill-ctype": "v1.22.1",
         "symfony/polyfill-iconv": "v1.22.1",
         "symfony/polyfill-intl-idn": "v1.22.1",
@@ -60,7 +60,7 @@
         "symfony/translation": "v4.4.24",
         "symfony/translation-contracts": "v2.4.0",
         "symfony/validator": "v4.4.24",
-        "symfony/var-dumper": "v5.2.8",
+        "symfony/var-dumper": "v5.3.0-RC1",
         "symfony/yaml": "v4.4.24",
         "twig/twig": "v2.14.6",
         "typo3/phar-stream-wrapper": "v3.1.6"
diff --git a/composer/Metapackage/DevDependencies/composer.json b/composer/Metapackage/DevDependencies/composer.json
index b9458d39b5223211735186aeeefd5eb68e67c40d..9eb0f0edeb34a63b24cd7c77328274bff38ba4e7 100644
--- a/composer/Metapackage/DevDependencies/composer.json
+++ b/composer/Metapackage/DevDependencies/composer.json
@@ -27,7 +27,7 @@
         "symfony/filesystem": "^4.4",
         "symfony/finder": "^4.4",
         "symfony/lock": "^4.4",
-        "symfony/phpunit-bridge": "^5.1.4",
-        "symfony/var-dumper": "^5.1.2"
+        "symfony/phpunit-bridge": "^5.3.0-rc1",
+        "symfony/var-dumper": "^5.3.0-rc1"
     }
 }
diff --git a/composer/Metapackage/PinnedDevDependencies/composer.json b/composer/Metapackage/PinnedDevDependencies/composer.json
index f769a5fc4be8f60b74844955f5d0e573e93e9fe8..f99fbae1b3087af2f6c963b914a15a1d8cf41d35 100644
--- a/composer/Metapackage/PinnedDevDependencies/composer.json
+++ b/composer/Metapackage/PinnedDevDependencies/composer.json
@@ -60,7 +60,7 @@
         "symfony/filesystem": "v4.4.22",
         "symfony/finder": "v4.4.24",
         "symfony/lock": "v4.4.23",
-        "symfony/phpunit-bridge": "v5.2.9",
+        "symfony/phpunit-bridge": "v5.3.0-RC1",
         "theseer/tokenizer": "1.2.0",
         "webmozart/assert": "1.10.0"
     }
diff --git a/core/composer.json b/core/composer.json
index 80d56099db37627b39fabf3202733ad3e9f685c6..b0677e756a2db565a44ff27ad5be716549e67021 100644
--- a/core/composer.json
+++ b/core/composer.json
@@ -23,7 +23,7 @@
         "symfony/event-dispatcher": "^4.4",
         "symfony/http-foundation": "^4.4.7",
         "symfony/http-kernel": "^4.4",
-        "symfony/mime": "^5.2",
+        "symfony/mime": "^5.3.0-rc1",
         "symfony/routing": "^4.4",
         "symfony/serializer": "^4.4",
         "symfony/translation": "^4.4",
diff --git a/core/tests/Drupal/BuildTests/Composer/Template/ComposerProjectTemplatesTest.php b/core/tests/Drupal/BuildTests/Composer/Template/ComposerProjectTemplatesTest.php
index 8e87252b938371415ef985ba3b04fae199fdc570..468069f8d8082edd8a6d502a9cc81a368d108339 100644
--- a/core/tests/Drupal/BuildTests/Composer/Template/ComposerProjectTemplatesTest.php
+++ b/core/tests/Drupal/BuildTests/Composer/Template/ComposerProjectTemplatesTest.php
@@ -32,7 +32,7 @@ class ComposerProjectTemplatesTest extends BuildTestBase {
    *
    * @see https://getcomposer.org/doc/04-schema.md#minimum-stability
    */
-  protected const MINIMUM_STABILITY = 'stable';
+  protected const MINIMUM_STABILITY = 'RC';
 
   /**
    * The order of stability strings from least stable to most stable.