diff --git a/src/Illuminate/Config/Repository.php b/src/Illuminate/Config/Repository.php
index 9788056c..2a8922d2 100755
--- a/src/Illuminate/Config/Repository.php
+++ b/src/Illuminate/Config/Repository.php
@@ -154,7 +154,7 @@ protected function load($group, $namespace, $collection)
 		// If we've already loaded this collection, we will just bail out since we do
 		// not want to load it again. Once items are loaded a first time they will
 		// stay kept in memory within this class and not loaded from disk again.
-		if (isset($this->afterLoad[$namespace]))
+		if ( ! is_null($namespace) && isset($this->afterLoad[$namespace]))
 		{
 			$items = $this->callAfterLoad($namespace, $group, $items);
 		}
diff --git a/src/Illuminate/Database/Eloquent/Collection.php b/src/Illuminate/Database/Eloquent/Collection.php
index 96dbbbeb..6ca90d91 100755
--- a/src/Illuminate/Database/Eloquent/Collection.php
+++ b/src/Illuminate/Database/Eloquent/Collection.php
@@ -1,5 +1,6 @@
 <?php namespace Illuminate\Database\Eloquent;
 
+use Illuminate\Support\Arr;
 use Illuminate\Support\Collection as BaseCollection;
 
 class Collection extends BaseCollection {
@@ -18,7 +19,7 @@ public function find($key, $default = null)
 			$key = $key->getKey();
 		}
 
-		return array_first($this->items, function($model, $itemKey) use ($key)
+		return Arr::first($this->items, function($model, $itemKey) use ($key)
 		{
 			return $model->getKey() == $key;
 
diff --git a/src/Illuminate/Database/Eloquent/Model.php b/src/Illuminate/Database/Eloquent/Model.php
index da9551a1..d677bf60 100755
--- a/src/Illuminate/Database/Eloquent/Model.php
+++ b/src/Illuminate/Database/Eloquent/Model.php
@@ -6,6 +6,7 @@
 use Carbon\Carbon;
 use Exception;
 use Illuminate\Database\Connection;
+use Illuminate\Support\Arr;
 use Illuminate\Support\Str;
 use LogicException;
 use JsonSerializable;
@@ -294,7 +295,7 @@ public static function hasGlobalScope($scope): bool
 	 */
 	public static function getGlobalScope($scope): ?ScopeInterface
     {
-		return array_first(static::$globalScopes[get_called_class()], function($value, $key) use ($scope)
+		return Arr::first(static::$globalScopes[get_called_class()], function($value, $key) use ($scope)
 		{
 			return $scope instanceof $value;
 		});
@@ -991,7 +992,7 @@ protected function getBelongsToManyCaller():?string
 	{
 		$self = __FUNCTION__;
 
-		$caller = array_first(debug_backtrace(false), function($trace, $key) use ($self)
+		$caller = Arr::first(debug_backtrace(false), function($trace, $key) use ($self)
 		{
 			$caller = $trace['function'];
 
diff --git a/src/Illuminate/Foundation/Application.php b/src/Illuminate/Foundation/Application.php
index 55e3790b..928bc0ba 100755
--- a/src/Illuminate/Foundation/Application.php
+++ b/src/Illuminate/Foundation/Application.php
@@ -1,6 +1,7 @@
 <?php namespace Illuminate\Foundation;
 
 use Closure;
+use Illuminate\Support\Arr;
 use Illuminate\Container\BindingResolutionException;
 use Illuminate\Foundation\Http\MiddlewareBuilder;
 use ReflectionException;
@@ -350,7 +351,7 @@ public function getRegistered($provider)
 
 		if (array_key_exists($name, $this->loadedProviders))
 		{
-			return array_first($this->serviceProviders, function($value, $key) use ($name)
+			return Arr::first($this->serviceProviders, function($value, $key) use ($name)
 			{
 				return get_class($value) == $name;
 			});
diff --git a/src/Illuminate/Foundation/EnvironmentDetector.php b/src/Illuminate/Foundation/EnvironmentDetector.php
index 8ce8ccc3..859e1947 100644
--- a/src/Illuminate/Foundation/EnvironmentDetector.php
+++ b/src/Illuminate/Foundation/EnvironmentDetector.php
@@ -1,5 +1,6 @@
 <?php namespace Illuminate\Foundation;
 
+use Illuminate\Support\Arr;
 use Closure;
 
 class EnvironmentDetector {
@@ -79,7 +80,7 @@ protected function detectConsoleEnvironment($environments, array $args): string
 	 */
 	protected function getEnvironmentArgument(array $args): ?string
     {
-		return array_first($args, function($value, $key)
+		return Arr::first($args, function($value, $key)
 		{
 			return starts_with($value, '--env');
 		});
diff --git a/src/Illuminate/Routing/Route.php b/src/Illuminate/Routing/Route.php
index 676725a2..4bf13752 100755
--- a/src/Illuminate/Routing/Route.php
+++ b/src/Illuminate/Routing/Route.php
@@ -5,6 +5,7 @@
 use Illuminate\Routing\Matching\HostValidator;
 use Illuminate\Routing\Matching\MethodValidator;
 use Illuminate\Routing\Matching\SchemeValidator;
+use Illuminate\Support\Arr;
 use Illuminate\Support\Str;
 use Symfony\Component\Routing\CompiledRoute;
 use Symfony\Component\Routing\Route as SymfonyRoute;
@@ -503,7 +504,7 @@ protected function parseAction($action)
 	 */
 	protected function findClosure(array $action)
 	{
-		return array_first($action, function($value, $key)
+		return Arr::first($action, function($value, $key)
 		{
 			return is_callable($value);
 		});
diff --git a/src/Illuminate/Routing/RouteCollection.php b/src/Illuminate/Routing/RouteCollection.php
index 393468ea..020027c3 100644
--- a/src/Illuminate/Routing/RouteCollection.php
+++ b/src/Illuminate/Routing/RouteCollection.php
@@ -1,5 +1,6 @@
 <?php namespace Illuminate\Routing;
 
+use Illuminate\Support\Arr;
 use Countable;
 use ArrayIterator;
 use IteratorAggregate;
@@ -221,7 +222,7 @@ protected function methodNotAllowed(array $others)
 	 */
 	protected function check(array $routes, $request, $includingMethod = true)
 	{
-		return array_first($routes, function($value, $key) use ($request, $includingMethod)
+		return Arr::first($routes, function($value, $key) use ($request, $includingMethod)
 		{
 			return $value->matches($request, $includingMethod);
 		});
diff --git a/src/Illuminate/Support/Collection.php b/src/Illuminate/Support/Collection.php
index d3a4e496..f7359001 100755
--- a/src/Illuminate/Support/Collection.php
+++ b/src/Illuminate/Support/Collection.php
@@ -149,7 +149,7 @@ public function first(?Closure $callback = null, $default = null)
 			return count($this->items) > 0 ? reset($this->items) : null;
 		}
 
-		return array_first($this->items, $callback, $default);
+		return Arr::first($this->items, $callback, $default);
 	}
 
 	/**
@@ -212,7 +212,7 @@ public function groupBy($groupBy)
 
 		foreach ($this->items as $key => $value)
 		{
-			$results[$this->getGroupByKey($groupBy, $key, $value)][] = $value;
+			$results[$this->getGroupByKey($groupBy, $key, $value) ?? ''][] = $value;
 		}
 
 		return new static($results);
diff --git a/src/Illuminate/Support/helpers.php b/src/Illuminate/Support/helpers.php
index 953e2008..3fbc00b5 100755
--- a/src/Illuminate/Support/helpers.php
+++ b/src/Illuminate/Support/helpers.php
@@ -177,6 +177,8 @@ function array_fetch($array, $key)
 	 * @param  \Closure  $callback
 	 * @param  mixed     $default
 	 * @return mixed
+	 *
+	 * @deprecated Use \Illuminate\Support\Arr::first() instead.
 	 */
 	function array_first($array, $callback, $default = null)
 	{
@@ -193,6 +195,8 @@ function array_first($array, $callback, $default = null)
 	 * @param  \Closure  $callback
 	 * @param  mixed     $default
 	 * @return mixed
+	 *
+	 * @deprecated Use \Illuminate\Support\Arr::last() instead.
 	 */
 	function array_last($array, $callback, $default = null)
 	{
diff --git a/src/Illuminate/View/Factory.php b/src/Illuminate/View/Factory.php
index 325bd457..f72c7e5f 100755
--- a/src/Illuminate/View/Factory.php
+++ b/src/Illuminate/View/Factory.php
@@ -3,6 +3,7 @@
 use Closure;
 use Illuminate\Events\Dispatcher;
 use Illuminate\Container\Container;
+use Illuminate\Support\Arr;
 use Illuminate\Support\Str;
 use Illuminate\View\Engines\EngineResolver;
 use Illuminate\Support\Contracts\ArrayableInterface as Arrayable;
@@ -272,7 +273,7 @@ protected function getExtension($path)
 	{
 		$extensions = array_keys($this->extensions);
 
-		return array_first($extensions, function($value, $key) use ($path)
+		return Arr::first($extensions, function($value, $key) use ($path)
 		{
 			return ends_with($path, $value);
 		});