diff --git a/CHANGELOG.md b/CHANGELOG.md
index 9dd9fa5ccd..78651654b1 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -2,6 +2,8 @@
 
 ## Unreleased
 
+- Add the `$customSamplingContext` argument to `Hub::startTransaction()` and `HubAdapter::startTransaction()` to fix deprecations thrown in Symfony (#1176)
+
 ## 3.1.2 (2021-01-08)
 
 - Fix unwanted call to the `before_send` callback with transaction events, use `traces_sampler` instead to filter transactions (#1158)
diff --git a/src/State/Hub.php b/src/State/Hub.php
index c24d59ef4e..611c72ed8a 100644
--- a/src/State/Hub.php
+++ b/src/State/Hub.php
@@ -213,15 +213,11 @@ public function getIntegration(string $className): ?IntegrationInterface
 
     /**
      * {@inheritdoc}
+     *
+     * @param array<string, mixed> $customSamplingContext Additional context that will be passed to the {@see SamplingContext}
      */
-    public function startTransaction(TransactionContext $context): Transaction
+    public function startTransaction(TransactionContext $context, array $customSamplingContext = []): Transaction
     {
-        $customSamplingContext = null;
-
-        if (\func_num_args() > 1) {
-            $customSamplingContext = func_get_arg(1);
-        }
-
         $transaction = new Transaction($context, $this);
         $client = $this->getClient();
         $options = null !== $client ? $client->getOptions() : null;
diff --git a/src/State/HubAdapter.php b/src/State/HubAdapter.php
index 7df115f9cd..65110fda37 100644
--- a/src/State/HubAdapter.php
+++ b/src/State/HubAdapter.php
@@ -153,11 +153,11 @@ public function getIntegration(string $className): ?IntegrationInterface
 
     /**
      * {@inheritdoc}
+     *
+     * @param array<string, mixed> $customSamplingContext Additional context that will be passed to the {@see SamplingContext}
      */
-    public function startTransaction(TransactionContext $context): Transaction
+    public function startTransaction(TransactionContext $context, array $customSamplingContext = []): Transaction
     {
-        $customSamplingContext = \func_num_args() > 1 ? func_get_arg(1) : [];
-
         /** @psalm-suppress TooManyArguments */
         return SentrySdk::getCurrentHub()->startTransaction($context, $customSamplingContext);
     }
diff --git a/tests/State/HubAdapterTest.php b/tests/State/HubAdapterTest.php
new file mode 100644
index 0000000000..8a83b411d4
--- /dev/null
+++ b/tests/State/HubAdapterTest.php
@@ -0,0 +1,282 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Sentry\Tests\State;
+
+use PHPUnit\Framework\TestCase;
+use Sentry\Breadcrumb;
+use Sentry\ClientInterface;
+use Sentry\Event;
+use Sentry\EventHint;
+use Sentry\EventId;
+use Sentry\Integration\IntegrationInterface;
+use Sentry\SentrySdk;
+use Sentry\Severity;
+use Sentry\State\HubAdapter;
+use Sentry\State\HubInterface;
+use Sentry\State\Scope;
+use Sentry\Tracing\Span;
+use Sentry\Tracing\Transaction;
+use Sentry\Tracing\TransactionContext;
+
+final class HubAdapterTest extends TestCase
+{
+    public function testGetInstance(): void
+    {
+        $this->assertSame(HubAdapter::getInstance(), HubAdapter::getInstance());
+    }
+
+    public function testGetInstanceReturnsUncloneableInstance(): void
+    {
+        $this->expectException(\BadMethodCallException::class);
+        $this->expectExceptionMessage('Cloning is forbidden.');
+
+        clone HubAdapter::getInstance();
+    }
+
+    public function testGetInstanceReturnsUnserializableInstance(): void
+    {
+        $this->expectException(\BadMethodCallException::class);
+        $this->expectExceptionMessage('Unserializing instances of this class is forbidden.');
+
+        unserialize(serialize(HubAdapter::getInstance()));
+    }
+
+    public function testGetClient(): void
+    {
+        $client = $this->createMock(ClientInterface::class);
+
+        SentrySdk::getCurrentHub()->bindClient($client);
+
+        $this->assertSame($client, HubAdapter::getInstance()->getClient());
+    }
+
+    public function testGetLastEventId(): void
+    {
+        $eventId = EventId::generate();
+
+        $hub = $this->createMock(HubInterface::class);
+        $hub->expects($this->once())
+            ->method('getLastEventId')
+            ->willReturn($eventId);
+
+        SentrySdk::setCurrentHub($hub);
+
+        $this->assertSame($eventId, HubAdapter::getInstance()->getLastEventId());
+    }
+
+    public function testPushScope(): void
+    {
+        $scope = new Scope();
+
+        $hub = $this->createMock(HubInterface::class);
+        $hub->expects($this->once())
+            ->method('pushScope')
+            ->willReturn($scope);
+
+        SentrySdk::setCurrentHub($hub);
+
+        $this->assertSame($scope, HubAdapter::getInstance()->pushScope());
+    }
+
+    public function testPopScope(): void
+    {
+        $hub = $this->createMock(HubInterface::class);
+        $hub->expects($this->once())
+            ->method('popScope')
+            ->willReturn(true);
+
+        SentrySdk::setCurrentHub($hub);
+
+        $this->assertTrue(HubAdapter::getInstance()->popScope());
+    }
+
+    public function testWithScope(): void
+    {
+        $callback = static function () {};
+
+        $hub = $this->createMock(HubInterface::class);
+        $hub->expects($this->once())
+            ->method('withScope')
+            ->with($callback);
+
+        SentrySdk::setCurrentHub($hub);
+        HubAdapter::getInstance()->withScope($callback);
+    }
+
+    public function testConfigureScope(): void
+    {
+        $callback = static function () {};
+
+        $hub = $this->createMock(HubInterface::class);
+        $hub->expects($this->once())
+            ->method('configureScope')
+            ->with($callback);
+
+        SentrySdk::setCurrentHub($hub);
+        HubAdapter::getInstance()->configureScope($callback);
+    }
+
+    public function testBindClient(): void
+    {
+        $client = $this->createMock(ClientInterface::class);
+
+        $hub = $this->createMock(HubInterface::class);
+        $hub->expects($this->once())
+            ->method('bindClient')
+            ->with($client);
+
+        SentrySdk::setCurrentHub($hub);
+        HubAdapter::getInstance()->bindClient($client);
+    }
+
+    public function testCaptureMessage(): void
+    {
+        $eventId = EventId::generate();
+
+        $hub = $this->createMock(HubInterface::class);
+        $hub->expects($this->once())
+            ->method('captureMessage')
+            ->with('foo', Severity::debug())
+            ->willReturn($eventId);
+
+        SentrySdk::setCurrentHub($hub);
+
+        $this->assertSame($eventId, HubAdapter::getInstance()->captureMessage('foo', Severity::debug()));
+    }
+
+    public function testCaptureException(): void
+    {
+        $eventId = EventId::generate();
+        $exception = new \Exception();
+
+        $hub = $this->createMock(HubInterface::class);
+        $hub->expects($this->once())
+            ->method('captureException')
+            ->with($exception)
+            ->willReturn($eventId);
+
+        SentrySdk::setCurrentHub($hub);
+
+        $this->assertSame($eventId, HubAdapter::getInstance()->captureException($exception));
+    }
+
+    public function testCaptureEvent(): void
+    {
+        $event = Event::createEvent();
+        $hint = EventHint::fromArray([]);
+
+        $hub = $this->createMock(HubInterface::class);
+        $hub->expects($this->once())
+            ->method('captureEvent')
+            ->with($event, $hint)
+            ->willReturn($event->getId());
+
+        SentrySdk::setCurrentHub($hub);
+
+        $this->assertSame($event->getId(), HubAdapter::getInstance()->captureEvent($event, $hint));
+    }
+
+    public function testCaptureLastError(): void
+    {
+        $eventId = EventId::generate();
+
+        $hub = $this->createMock(HubInterface::class);
+        $hub->expects($this->once())
+            ->method('captureLastError')
+            ->willReturn($eventId);
+
+        SentrySdk::setCurrentHub($hub);
+
+        $this->assertSame($eventId, HubAdapter::getInstance()->captureLastError());
+    }
+
+    public function testAddBreadcrumb(): void
+    {
+        $breadcrumb = new Breadcrumb(Breadcrumb::LEVEL_DEBUG, Breadcrumb::TYPE_ERROR, 'user');
+
+        $hub = $this->createMock(HubInterface::class);
+        $hub->expects($this->once())
+            ->method('addBreadcrumb')
+            ->willReturn(true);
+
+        SentrySdk::setCurrentHub($hub);
+
+        $this->assertTrue(HubAdapter::getInstance()->addBreadcrumb($breadcrumb));
+    }
+
+    public function testGetIntegration(): void
+    {
+        $integration = $this->createMock(IntegrationInterface::class);
+
+        $hub = $this->createMock(HubInterface::class);
+        $hub->expects($this->once())
+            ->method('getIntegration')
+            ->with(\get_class($integration))
+            ->willReturn($integration);
+
+        SentrySdk::setCurrentHub($hub);
+
+        $this->assertSame($integration, HubAdapter::getInstance()->getIntegration(\get_class($integration)));
+    }
+
+    public function testStartTransaction(): void
+    {
+        $transactionContext = new TransactionContext();
+        $transaction = new Transaction($transactionContext);
+
+        $hub = $this->createMock(HubInterface::class);
+        $hub->expects($this->once())
+            ->method('startTransaction')
+            ->with($transactionContext)
+            ->willReturn($transaction);
+
+        SentrySdk::setCurrentHub($hub);
+
+        $this->assertSame($transaction, HubAdapter::getInstance()->startTransaction($transactionContext));
+    }
+
+    public function testGetTransaction(): void
+    {
+        $transaction = new Transaction(new TransactionContext());
+
+        $hub = $this->createMock(HubInterface::class);
+        $hub->expects($this->once())
+            ->method('getTransaction')
+            ->willReturn($transaction);
+
+        SentrySdk::setCurrentHub($hub);
+
+        $this->assertSame($transaction, HubAdapter::getInstance()->getTransaction());
+    }
+
+    public function testGetSpan(): void
+    {
+        $span = new Span();
+
+        $hub = $this->createMock(HubInterface::class);
+        $hub->expects($this->once())
+            ->method('getSpan')
+            ->willReturn($span);
+
+        SentrySdk::setCurrentHub($hub);
+
+        $this->assertSame($span, HubAdapter::getInstance()->getSpan());
+    }
+
+    public function testSetSpan(): void
+    {
+        $span = new Span();
+
+        $hub = $this->createMock(HubInterface::class);
+        $hub->expects($this->once())
+            ->method('setSpan')
+            ->with($span)
+            ->willReturn($hub);
+
+        SentrySdk::setCurrentHub($hub);
+
+        $this->assertSame($hub, HubAdapter::getInstance()->setSpan($span));
+    }
+}