diff --git a/.github/CONTRIBUTING.md b/.github/CONTRIBUTING.md
index 8f525a97f..7f161bd79 100644
--- a/.github/CONTRIBUTING.md
+++ b/.github/CONTRIBUTING.md
@@ -41,7 +41,7 @@ To achieve this, you need to acquire the Composer source code:
 2. Download the [`composer.phar`](https://getcomposer.org/composer.phar) executable
 3. Run Composer to get the dependencies: `cd composer && php ../composer.phar install`
 
-You can run the test suite by executing `vendor/bin/phpunit` when inside the
+You can run the test suite by executing `vendor/bin/simple-phpunit` when inside the
 composer directory, and run Composer by executing the `bin/composer`. To test
 your modified Composer code against another project, run `php
 /path/to/composer/bin/composer` inside that project's directory.
diff --git a/composer.json b/composer.json
index 45a28aba7..7705678ac 100644
--- a/composer.json
+++ b/composer.json
@@ -32,14 +32,14 @@
         "psr/log": "^1.0",
         "seld/jsonlint": "^1.4",
         "seld/phar-utils": "^1.0",
-        "symfony/console": "^2.8.52 || ^3.4.35 || ^4.4 || ^5.0",
-        "symfony/filesystem": "^2.8.52 || ^3.4.35 || ^4.4 || ^5.0",
-        "symfony/finder": "^2.8.52 || ^3.4.35 || ^4.4 || ^5.0",
-        "symfony/process": "^2.8.52 || ^3.4.35 || ^4.4 || ^5.0",
+        "symfony/console": "^2.8.52 || ^3.4.35 || ^4.4 || ^5.0 || ^6.0",
+        "symfony/filesystem": "^2.8.52 || ^3.4.35 || ^4.4 || ^5.0 || ^6.0",
+        "symfony/finder": "^2.8.52 || ^3.4.35 || ^4.4 || ^5.0 || ^6.0",
+        "symfony/process": "^2.8.52 || ^3.4.35 || ^4.4 || ^5.0 || ^6.0",
         "react/promise": "^1.2 || ^2.7"
     },
     "require-dev": {
-        "symfony/phpunit-bridge": "^4.2 || ^5.0",
+        "symfony/phpunit-bridge": "^4.2 || ^5.0 || ^6.0",
         "phpspec/prophecy": "^1.10"
     },
     "suggest": {
diff --git a/composer.lock b/composer.lock
index 447827707..b17aa8895 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": "9ca39897cc82c83aa794920b6c2f0a60",
+    "content-hash": "bff3f5b355e45125612dff36a8f71737",
     "packages": [
         {
             "name": "composer/ca-bundle",
diff --git a/res/composer-schema.json b/res/composer-schema.json
index 7aa8fbd1a..c5e3376ee 100644
--- a/res/composer-schema.json
+++ b/res/composer-schema.json
@@ -1,6 +1,6 @@
 {
     "$schema": "https://json-schema.org/draft-04/schema#",
-    "name": "Package",
+    "title": "Package",
     "type": "object",
     "additionalProperties": false,
     "required": [ "name", "description" ],
@@ -42,7 +42,7 @@
         "version": {
             "type": "string",
             "description": "Package version, see https://getcomposer.org/doc/04-schema.md#version for more info on valid schemes.",
-            "pattern": "^v?\\d+(((\\.\\d+)?\\.\\d+)?\\.\\d+)?|^dev-"
+            "pattern": "^v?\\d+(\\.\\d+){0,3}|^dev-"
         },
         "time": {
             "type": "string",
@@ -397,7 +397,7 @@
         "minimum-stability": {
             "type": ["string"],
             "description": "The minimum stability the packages must have to be install-able. Possible values are: dev, alpha, beta, RC, stable.",
-            "pattern": "^dev|alpha|beta|rc|RC|stable$"
+            "enum": ["dev", "alpha", "beta", "rc", "RC", "stable"]
         },
         "prefer-stable": {
             "type": ["boolean"],
diff --git a/src/Composer/Installer/BinaryInstaller.php b/src/Composer/Installer/BinaryInstaller.php
index 4ce134b94..afb1608dc 100644
--- a/src/Composer/Installer/BinaryInstaller.php
+++ b/src/Composer/Installer/BinaryInstaller.php
@@ -53,6 +53,9 @@ class BinaryInstaller
         if (!$binaries) {
             return;
         }
+
+        Platform::workaroundFilesystemIssues();
+
         foreach ($binaries as $bin) {
             $binPath = $installPath.'/'.$bin;
             if (!file_exists($binPath)) {
diff --git a/src/Composer/Util/ProcessExecutor.php b/src/Composer/Util/ProcessExecutor.php
index 5ba2e57eb..1922e6c1b 100644
--- a/src/Composer/Util/ProcessExecutor.php
+++ b/src/Composer/Util/ProcessExecutor.php
@@ -251,16 +251,32 @@ class ProcessExecutor
             throw new \RuntimeException('The given CWD for the process does not exist: '.$cwd);
         }
 
-        // TODO in v3, commands should be passed in as arrays of cmd + args
-        if (method_exists('Symfony\Component\Process\Process', 'fromShellCommandline')) {
-            $process = Process::fromShellCommandline($command, $cwd, null, null, static::getTimeout());
-        } else {
-            $process = new Process($command, $cwd, null, null, static::getTimeout());
+        try {
+            // TODO in v3, commands should be passed in as arrays of cmd + args
+            if (method_exists('Symfony\Component\Process\Process', 'fromShellCommandline')) {
+                $process = Process::fromShellCommandline($command, $cwd, null, null, static::getTimeout());
+            } else {
+                $process = new Process($command, $cwd, null, null, static::getTimeout());
+            }
+        } catch (\Exception $e) {
+            call_user_func($job['reject'], $e);
+            return;
+        } catch (\Throwable $e) {
+            call_user_func($job['reject'], $e);
+            return;
         }
 
         $job['process'] = $process;
 
-        $process->start();
+        try {
+            $process->start();
+        } catch (\Exception $e) {
+            call_user_func($job['reject'], $e);
+            return;
+        } catch (\Throwable $e) {
+            call_user_func($job['reject'], $e);
+            return;
+        }
     }
 
     public function wait($index = null)
diff --git a/tests/Composer/Test/Json/ComposerSchemaTest.php b/tests/Composer/Test/Json/ComposerSchemaTest.php
index 687c1137a..0eece664c 100644
--- a/tests/Composer/Test/Json/ComposerSchemaTest.php
+++ b/tests/Composer/Test/Json/ComposerSchemaTest.php
@@ -71,25 +71,23 @@ class ComposerSchemaTest extends TestCase
 
     public function testMinimumStabilityValues()
     {
-        $json = '{ "name": "vendor/package", "description": "generic description", "minimum-stability": "" }';
-        $this->assertEquals(array(
+        $expectedError = array(
             array(
                 'property' => 'minimum-stability',
-                'message' => 'Does not match the regex pattern ^dev|alpha|beta|rc|RC|stable$',
-                'constraint' => 'pattern',
-                'pattern' => '^dev|alpha|beta|rc|RC|stable$',
+                'message' => 'Does not have a value in the enumeration ["dev","alpha","beta","rc","RC","stable"]',
+                'constraint' => 'enum',
+                'enum' => array('dev', 'alpha', 'beta', 'rc', 'RC', 'stable'),
             ),
-        ), $this->check($json), 'empty string');
+        );
+
+        $json = '{ "name": "vendor/package", "description": "generic description", "minimum-stability": "" }';
+        $this->assertEquals($expectedError, $this->check($json), 'empty string');
 
         $json = '{ "name": "vendor/package", "description": "generic description", "minimum-stability": "dummy" }';
-        $this->assertEquals(array(
-            array(
-                'property' => 'minimum-stability',
-                'message' => 'Does not match the regex pattern ^dev|alpha|beta|rc|RC|stable$',
-                'constraint' => 'pattern',
-                'pattern' => '^dev|alpha|beta|rc|RC|stable$',
-            ),
-        ), $this->check($json), 'dummy');
+        $this->assertEquals($expectedError, $this->check($json), 'dummy');
+
+        $json = '{ "name": "vendor/package", "description": "generic description", "minimum-stability": "devz" }';
+        $this->assertEquals($expectedError, $this->check($json), 'devz');
 
         $json = '{ "name": "vendor/package", "description": "generic description", "minimum-stability": "dev" }';
         $this->assertTrue($this->check($json), 'dev');