diff --git a/src/Symfony/Component/Notifier/Tests/Transport/DsnTest.php b/src/Symfony/Component/Notifier/Tests/Transport/DsnTest.php
new file mode 100644
index 0000000000000..fc7072dee68ec
--- /dev/null
+++ b/src/Symfony/Component/Notifier/Tests/Transport/DsnTest.php
@@ -0,0 +1,123 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Symfony\Component\Notifier\Tests\Transport;
+
+use PHPUnit\Framework\TestCase;
+use Symfony\Component\Notifier\Exception\InvalidArgumentException;
+use Symfony\Component\Notifier\Transport\Dsn;
+
+final class DsnTest extends TestCase
+{
+    /**
+     * @dataProvider fromStringProvider
+     */
+    public function testFromString(string $string, Dsn $expectedDsn)
+    {
+        $actualDsn = Dsn::fromString($string);
+
+        $this->assertSame($expectedDsn->getScheme(), $actualDsn->getScheme());
+        $this->assertSame($expectedDsn->getHost(), $actualDsn->getHost());
+        $this->assertSame($expectedDsn->getPort(), $actualDsn->getPort());
+        $this->assertSame($expectedDsn->getUser(), $actualDsn->getUser());
+        $this->assertSame($expectedDsn->getPassword(), $actualDsn->getPassword());
+        $this->assertSame($expectedDsn->getPath(), $actualDsn->getPath());
+        $this->assertSame($expectedDsn->getOption('from'), $actualDsn->getOption('from'));
+
+        $this->assertSame($string, $actualDsn->getOriginalDsn());
+    }
+
+    public function fromStringProvider(): iterable
+    {
+        yield 'simple dsn' => [
+            'scheme://localhost',
+            new Dsn('scheme', 'localhost', null, null, null, [], null),
+        ];
+
+        yield 'simple dsn including @ sign, but no user/password/token' => [
+            'scheme://@localhost',
+            new Dsn('scheme', 'localhost', null, null),
+        ];
+
+        yield 'simple dsn including : sign and @ sign, but no user/password/token' => [
+            'scheme://:@localhost',
+            new Dsn('scheme', 'localhost', null, null),
+        ];
+
+        yield 'simple dsn including user, : sign and @ sign, but no password' => [
+            'scheme://user1:@localhost',
+            new Dsn('scheme', 'localhost', 'user1', null),
+        ];
+
+        yield 'simple dsn including : sign, password, and @ sign, but no user' => [
+            'scheme://:pass@localhost',
+            new Dsn('scheme', 'localhost', null, 'pass'),
+        ];
+
+        yield 'dsn with user and pass' => [
+            'scheme://u$er:pa$s@localhost',
+            new Dsn('scheme', 'localhost', 'u$er', 'pa$s', null, [], null),
+        ];
+
+        yield 'dsn with user and pass and custom port' => [
+            'scheme://u$er:pa$s@localhost:8000',
+            new Dsn('scheme', 'localhost', 'u$er', 'pa$s', '8000', [], null),
+        ];
+
+        yield 'dsn with user and pass, custom port and custom path' => [
+            'scheme://u$er:pa$s@localhost:8000/channel',
+            new Dsn('scheme', 'localhost', 'u$er', 'pa$s', '8000', [], '/channel'),
+        ];
+
+        yield 'dsn with user and pass, custom port, custom path and custom options' => [
+            'scheme://u$er:pa$s@localhost:8000/channel?from=FROM',
+            new Dsn('scheme', 'localhost', 'u$er', 'pa$s', '8000', ['from' => 'FROM'], '/channel'),
+        ];
+    }
+
+    /**
+     * @dataProvider invalidDsnProvider
+     */
+    public function testInvalidDsn(string $dsn, string $exceptionMessage)
+    {
+        $this->expectException(InvalidArgumentException::class);
+        $this->expectExceptionMessage($exceptionMessage);
+        Dsn::fromString($dsn);
+    }
+
+    public function invalidDsnProvider(): iterable
+    {
+        yield [
+            'some://',
+            'The "some://" notifier DSN is invalid.',
+        ];
+
+        yield [
+            '//slack',
+            'The "//slack" notifier DSN must contain a scheme.',
+        ];
+
+        yield [
+            'file:///some/path',
+            'The "file:///some/path" notifier DSN must contain a host (use "default" by default).',
+        ];
+    }
+
+    public function testGetOption()
+    {
+        $options = ['with_value' => 'some value', 'nullable' => null];
+        $dsn = new Dsn('scheme', 'localhost', 'u$er', 'pa$s', '8000', $options, '/channel');
+
+        $this->assertSame('some value', $dsn->getOption('with_value'));
+        $this->assertSame('default', $dsn->getOption('nullable', 'default'));
+        $this->assertSame('default', $dsn->getOption('not_existent_property', 'default'));
+    }
+}
diff --git a/src/Symfony/Component/Notifier/Transport/Dsn.php b/src/Symfony/Component/Notifier/Transport/Dsn.php
index c18bc600e29d2..a8c556e8f620e 100644
--- a/src/Symfony/Component/Notifier/Transport/Dsn.php
+++ b/src/Symfony/Component/Notifier/Transport/Dsn.php
@@ -54,8 +54,8 @@ public static function fromString(string $dsn): self
             throw new InvalidArgumentException(sprintf('The "%s" notifier DSN must contain a host (use "default" by default).', $dsn));
         }
 
-        $user = isset($parsedDsn['user']) ? urldecode($parsedDsn['user']) : null;
-        $password = isset($parsedDsn['pass']) ? urldecode($parsedDsn['pass']) : null;
+        $user = '' !== ($parsedDsn['user'] ?? '') ? urldecode($parsedDsn['user']) : null;
+        $password = '' !== ($parsedDsn['pass'] ?? '') ? urldecode($parsedDsn['pass']) : null;
         $port = $parsedDsn['port'] ?? null;
         $path = $parsedDsn['path'] ?? null;
         parse_str($parsedDsn['query'] ?? '', $query);