diff --git a/OmekaAmazonS3StorageAdapterPlugin.php b/OmekaAmazonS3StorageAdapterPlugin.php
new file mode 100755
index 0000000..b97552d
--- /dev/null
+++ b/OmekaAmazonS3StorageAdapterPlugin.php
@@ -0,0 +1,12 @@
+<?php
+
+/**
+ * @copyright 2016 King's College London
+ * @license: https://joinup.ec.europa.eu/community/eupl/og_page/eupl
+ */
+require_once('vendor/autoload.php');
+require_once('libraries/Omeka/Storage/Adapter/AmazonS3.php');
+
+class OmekaAmazonS3StorageAdapterPlugin extends Omeka_Plugin_AbstractPlugin
+{
+}
diff --git a/README.md b/README.md
index 5f0e496..4e14df7 100644
--- a/README.md
+++ b/README.md
@@ -14,9 +14,10 @@ The main differences are:
 
 ## Usage
 
-1. Install the plugin by extracting it to the `plugins` directory in your Omeka instance and enabling
-   in admin/plugins
-2. Add the following to your Omeka `application/configuration/config.ini` file:
+1. Download repo as a zip file and extract it to a folder named `OmekaAmazonS3StorageAdapter` in the `plugins` directory in your Omeka instance.
+2. Run `composer install` within the plugin's folder to install the Amazon S3 PHP SDK.
+3. Enable the plugin in admin/plugins
+4. Add the following to your Omeka `application/configuration/config.ini` file:
 
 ```
 storage.adapter = Omeka_Storage_Adapter_AmazonS3
diff --git a/composer.lock b/composer.lock
index 79dc993..d96e0a0 100644
--- a/composer.lock
+++ b/composer.lock
@@ -4,36 +4,93 @@
         "Read more about it at https://getcomposer.org/doc/01-basic-usage.md#installing-dependencies",
         "This file is @generated automatically"
     ],
-    "content-hash": "d533f66b8804906be64343ace5c924f7",
+    "content-hash": "39bbd38315368506c27f9f108f691704",
     "packages": [
+        {
+            "name": "aws/aws-crt-php",
+            "version": "v1.2.1",
+            "source": {
+                "type": "git",
+                "url": "https://github.com/awslabs/aws-crt-php.git",
+                "reference": "1926277fc71d253dfa820271ac5987bdb193ccf5"
+            },
+            "dist": {
+                "type": "zip",
+                "url": "https://api.github.com/repos/awslabs/aws-crt-php/zipball/1926277fc71d253dfa820271ac5987bdb193ccf5",
+                "reference": "1926277fc71d253dfa820271ac5987bdb193ccf5",
+                "shasum": ""
+            },
+            "require": {
+                "php": ">=5.5"
+            },
+            "require-dev": {
+                "phpunit/phpunit": "^4.8.35||^5.6.3||^9.5",
+                "yoast/phpunit-polyfills": "^1.0"
+            },
+            "suggest": {
+                "ext-awscrt": "Make sure you install awscrt native extension to use any of the functionality."
+            },
+            "type": "library",
+            "autoload": {
+                "classmap": [
+                    "src/"
+                ]
+            },
+            "notification-url": "https://packagist.org/downloads/",
+            "license": [
+                "Apache-2.0"
+            ],
+            "authors": [
+                {
+                    "name": "AWS SDK Common Runtime Team",
+                    "email": "aws-sdk-common-runtime@amazon.com"
+                }
+            ],
+            "description": "AWS Common Runtime for PHP",
+            "homepage": "https://github.com/awslabs/aws-crt-php",
+            "keywords": [
+                "amazon",
+                "aws",
+                "crt",
+                "sdk"
+            ],
+            "support": {
+                "issues": "https://github.com/awslabs/aws-crt-php/issues",
+                "source": "https://github.com/awslabs/aws-crt-php/tree/v1.2.1"
+            },
+            "time": "2023-03-24T20:22:19+00:00"
+        },
         {
             "name": "aws/aws-sdk-php",
-            "version": "3.173.2",
+            "version": "3.263.4",
             "source": {
                 "type": "git",
                 "url": "https://github.com/aws/aws-sdk-php.git",
-                "reference": "1ab4f565744aea8e9560ee8aaffb19b87238c7d5"
+                "reference": "08e2f243243a9fcdd8909d596e46f81d8c72cb60"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/aws/aws-sdk-php/zipball/1ab4f565744aea8e9560ee8aaffb19b87238c7d5",
-                "reference": "1ab4f565744aea8e9560ee8aaffb19b87238c7d5",
+                "url": "https://api.github.com/repos/aws/aws-sdk-php/zipball/08e2f243243a9fcdd8909d596e46f81d8c72cb60",
+                "reference": "08e2f243243a9fcdd8909d596e46f81d8c72cb60",
                 "shasum": ""
             },
             "require": {
+                "aws/aws-crt-php": "^1.0.4",
                 "ext-json": "*",
                 "ext-pcre": "*",
                 "ext-simplexml": "*",
-                "guzzlehttp/guzzle": "^5.3.3|^6.2.1|^7.0",
-                "guzzlehttp/promises": "^1.0",
-                "guzzlehttp/psr7": "^1.4.1",
-                "mtdowling/jmespath.php": "^2.5",
+                "guzzlehttp/guzzle": "^6.5.8 || ^7.4.5",
+                "guzzlehttp/promises": "^1.4.0",
+                "guzzlehttp/psr7": "^1.8.5 || ^2.3",
+                "mtdowling/jmespath.php": "^2.6",
                 "php": ">=5.5"
             },
             "require-dev": {
                 "andrewsville/php-token-reflection": "^1.4",
                 "aws/aws-php-sns-message-validator": "~1.0",
                 "behat/behat": "~3.0",
+                "composer/composer": "^1.10.22",
+                "dms/phpunit-arraysubset-asserts": "^0.4.0",
                 "doctrine/cache": "~1.4",
                 "ext-dom": "*",
                 "ext-openssl": "*",
@@ -41,10 +98,11 @@
                 "ext-sockets": "*",
                 "nette/neon": "^2.3",
                 "paragonie/random_compat": ">= 2",
-                "phpunit/phpunit": "^4.8.35|^5.4.3",
+                "phpunit/phpunit": "^4.8.35 || ^5.6.3 || ^9.5",
                 "psr/cache": "^1.0",
                 "psr/simple-cache": "^1.0",
-                "sebastian/comparator": "^1.2.3"
+                "sebastian/comparator": "^1.2.3 || ^4.0",
+                "yoast/phpunit-polyfills": "^1.0"
             },
             "suggest": {
                 "aws/aws-php-sns-message-validator": "To validate incoming SNS notifications",
@@ -60,12 +118,12 @@
                 }
             },
             "autoload": {
-                "psr-4": {
-                    "Aws\\": "src/"
-                },
                 "files": [
                     "src/functions.php"
-                ]
+                ],
+                "psr-4": {
+                    "Aws\\": "src/"
+                }
             },
             "notification-url": "https://packagist.org/downloads/",
             "license": [
@@ -89,37 +147,44 @@
                 "s3",
                 "sdk"
             ],
-            "time": "2021-02-03T21:12:51+00:00"
+            "support": {
+                "forum": "https://forums.aws.amazon.com/forum.jspa?forumID=80",
+                "issues": "https://github.com/aws/aws-sdk-php/issues",
+                "source": "https://github.com/aws/aws-sdk-php/tree/3.263.4"
+            },
+            "time": "2023-04-05T18:21:54+00:00"
         },
         {
             "name": "guzzlehttp/guzzle",
-            "version": "7.2.0",
+            "version": "7.5.0",
             "source": {
                 "type": "git",
                 "url": "https://github.com/guzzle/guzzle.git",
-                "reference": "0aa74dfb41ae110835923ef10a9d803a22d50e79"
+                "reference": "b50a2a1251152e43f6a37f0fa053e730a67d25ba"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/guzzle/guzzle/zipball/0aa74dfb41ae110835923ef10a9d803a22d50e79",
-                "reference": "0aa74dfb41ae110835923ef10a9d803a22d50e79",
+                "url": "https://api.github.com/repos/guzzle/guzzle/zipball/b50a2a1251152e43f6a37f0fa053e730a67d25ba",
+                "reference": "b50a2a1251152e43f6a37f0fa053e730a67d25ba",
                 "shasum": ""
             },
             "require": {
                 "ext-json": "*",
-                "guzzlehttp/promises": "^1.4",
-                "guzzlehttp/psr7": "^1.7",
+                "guzzlehttp/promises": "^1.5",
+                "guzzlehttp/psr7": "^1.9 || ^2.4",
                 "php": "^7.2.5 || ^8.0",
-                "psr/http-client": "^1.0"
+                "psr/http-client": "^1.0",
+                "symfony/deprecation-contracts": "^2.2 || ^3.0"
             },
             "provide": {
                 "psr/http-client-implementation": "1.0"
             },
             "require-dev": {
+                "bamarni/composer-bin-plugin": "^1.8.1",
                 "ext-curl": "*",
                 "php-http/client-integration-tests": "^3.0",
-                "phpunit/phpunit": "^8.5.5 || ^9.3.5",
-                "psr/log": "^1.1"
+                "phpunit/phpunit": "^8.5.29 || ^9.5.23",
+                "psr/log": "^1.1 || ^2.0 || ^3.0"
             },
             "suggest": {
                 "ext-curl": "Required for CURL handler support",
@@ -128,36 +193,64 @@
             },
             "type": "library",
             "extra": {
+                "bamarni-bin": {
+                    "bin-links": true,
+                    "forward-command": false
+                },
                 "branch-alias": {
-                    "dev-master": "7.1-dev"
+                    "dev-master": "7.5-dev"
                 }
             },
             "autoload": {
-                "psr-4": {
-                    "GuzzleHttp\\": "src/"
-                },
                 "files": [
                     "src/functions_include.php"
-                ]
+                ],
+                "psr-4": {
+                    "GuzzleHttp\\": "src/"
+                }
             },
             "notification-url": "https://packagist.org/downloads/",
             "license": [
                 "MIT"
             ],
             "authors": [
+                {
+                    "name": "Graham Campbell",
+                    "email": "hello@gjcampbell.co.uk",
+                    "homepage": "https://github.com/GrahamCampbell"
+                },
                 {
                     "name": "Michael Dowling",
                     "email": "mtdowling@gmail.com",
                     "homepage": "https://github.com/mtdowling"
                 },
+                {
+                    "name": "Jeremy Lindblom",
+                    "email": "jeremeamia@gmail.com",
+                    "homepage": "https://github.com/jeremeamia"
+                },
+                {
+                    "name": "George Mponos",
+                    "email": "gmponos@gmail.com",
+                    "homepage": "https://github.com/gmponos"
+                },
+                {
+                    "name": "Tobias Nyholm",
+                    "email": "tobias.nyholm@gmail.com",
+                    "homepage": "https://github.com/Nyholm"
+                },
                 {
                     "name": "Márk Sági-Kazár",
                     "email": "mark.sagikazar@gmail.com",
-                    "homepage": "https://sagikazarmark.hu"
+                    "homepage": "https://github.com/sagikazarmark"
+                },
+                {
+                    "name": "Tobias Schultze",
+                    "email": "webmaster@tubo-world.de",
+                    "homepage": "https://github.com/Tobion"
                 }
             ],
             "description": "Guzzle is a PHP HTTP client library",
-            "homepage": "http://guzzlephp.org/",
             "keywords": [
                 "client",
                 "curl",
@@ -169,6 +262,10 @@
                 "rest",
                 "web service"
             ],
+            "support": {
+                "issues": "https://github.com/guzzle/guzzle/issues",
+                "source": "https://github.com/guzzle/guzzle/tree/7.5.0"
+            },
             "funding": [
                 {
                     "url": "https://github.com/GrahamCampbell",
@@ -179,28 +276,24 @@
                     "type": "github"
                 },
                 {
-                    "url": "https://github.com/alexeyshockov",
-                    "type": "github"
-                },
-                {
-                    "url": "https://github.com/gmponos",
-                    "type": "github"
+                    "url": "https://tidelift.com/funding/github/packagist/guzzlehttp/guzzle",
+                    "type": "tidelift"
                 }
             ],
-            "time": "2020-10-10T11:47:56+00:00"
+            "time": "2022-08-28T15:39:27+00:00"
         },
         {
             "name": "guzzlehttp/promises",
-            "version": "1.4.0",
+            "version": "1.5.2",
             "source": {
                 "type": "git",
                 "url": "https://github.com/guzzle/promises.git",
-                "reference": "60d379c243457e073cff02bc323a2a86cb355631"
+                "reference": "b94b2807d85443f9719887892882d0329d1e2598"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/guzzle/promises/zipball/60d379c243457e073cff02bc323a2a86cb355631",
-                "reference": "60d379c243457e073cff02bc323a2a86cb355631",
+                "url": "https://api.github.com/repos/guzzle/promises/zipball/b94b2807d85443f9719887892882d0329d1e2598",
+                "reference": "b94b2807d85443f9719887892882d0329d1e2598",
                 "shasum": ""
             },
             "require": {
@@ -212,90 +305,153 @@
             "type": "library",
             "extra": {
                 "branch-alias": {
-                    "dev-master": "1.4-dev"
+                    "dev-master": "1.5-dev"
                 }
             },
             "autoload": {
-                "psr-4": {
-                    "GuzzleHttp\\Promise\\": "src/"
-                },
                 "files": [
                     "src/functions_include.php"
-                ]
+                ],
+                "psr-4": {
+                    "GuzzleHttp\\Promise\\": "src/"
+                }
             },
             "notification-url": "https://packagist.org/downloads/",
             "license": [
                 "MIT"
             ],
             "authors": [
+                {
+                    "name": "Graham Campbell",
+                    "email": "hello@gjcampbell.co.uk",
+                    "homepage": "https://github.com/GrahamCampbell"
+                },
                 {
                     "name": "Michael Dowling",
                     "email": "mtdowling@gmail.com",
                     "homepage": "https://github.com/mtdowling"
+                },
+                {
+                    "name": "Tobias Nyholm",
+                    "email": "tobias.nyholm@gmail.com",
+                    "homepage": "https://github.com/Nyholm"
+                },
+                {
+                    "name": "Tobias Schultze",
+                    "email": "webmaster@tubo-world.de",
+                    "homepage": "https://github.com/Tobion"
                 }
             ],
             "description": "Guzzle promises library",
             "keywords": [
                 "promise"
             ],
-            "time": "2020-09-30T07:37:28+00:00"
+            "support": {
+                "issues": "https://github.com/guzzle/promises/issues",
+                "source": "https://github.com/guzzle/promises/tree/1.5.2"
+            },
+            "funding": [
+                {
+                    "url": "https://github.com/GrahamCampbell",
+                    "type": "github"
+                },
+                {
+                    "url": "https://github.com/Nyholm",
+                    "type": "github"
+                },
+                {
+                    "url": "https://tidelift.com/funding/github/packagist/guzzlehttp/promises",
+                    "type": "tidelift"
+                }
+            ],
+            "time": "2022-08-28T14:55:35+00:00"
         },
         {
             "name": "guzzlehttp/psr7",
-            "version": "1.7.0",
+            "version": "2.4.4",
             "source": {
                 "type": "git",
                 "url": "https://github.com/guzzle/psr7.git",
-                "reference": "53330f47520498c0ae1f61f7e2c90f55690c06a3"
+                "reference": "3cf1b6d4f0c820a2cf8bcaec39fc698f3443b5cf"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/guzzle/psr7/zipball/53330f47520498c0ae1f61f7e2c90f55690c06a3",
-                "reference": "53330f47520498c0ae1f61f7e2c90f55690c06a3",
+                "url": "https://api.github.com/repos/guzzle/psr7/zipball/3cf1b6d4f0c820a2cf8bcaec39fc698f3443b5cf",
+                "reference": "3cf1b6d4f0c820a2cf8bcaec39fc698f3443b5cf",
                 "shasum": ""
             },
             "require": {
-                "php": ">=5.4.0",
-                "psr/http-message": "~1.0",
-                "ralouphie/getallheaders": "^2.0.5 || ^3.0.0"
+                "php": "^7.2.5 || ^8.0",
+                "psr/http-factory": "^1.0",
+                "psr/http-message": "^1.0",
+                "ralouphie/getallheaders": "^3.0"
             },
             "provide": {
+                "psr/http-factory-implementation": "1.0",
                 "psr/http-message-implementation": "1.0"
             },
             "require-dev": {
-                "ext-zlib": "*",
-                "phpunit/phpunit": "~4.8.36 || ^5.7.27 || ^6.5.14 || ^7.5.20 || ^8.5.8 || ^9.3.10"
+                "bamarni/composer-bin-plugin": "^1.8.1",
+                "http-interop/http-factory-tests": "^0.9",
+                "phpunit/phpunit": "^8.5.29 || ^9.5.23"
             },
             "suggest": {
                 "laminas/laminas-httphandlerrunner": "Emit PSR-7 responses"
             },
             "type": "library",
             "extra": {
+                "bamarni-bin": {
+                    "bin-links": true,
+                    "forward-command": false
+                },
                 "branch-alias": {
-                    "dev-master": "1.7-dev"
+                    "dev-master": "2.4-dev"
                 }
             },
             "autoload": {
                 "psr-4": {
                     "GuzzleHttp\\Psr7\\": "src/"
-                },
-                "files": [
-                    "src/functions_include.php"
-                ]
+                }
             },
             "notification-url": "https://packagist.org/downloads/",
             "license": [
                 "MIT"
             ],
             "authors": [
+                {
+                    "name": "Graham Campbell",
+                    "email": "hello@gjcampbell.co.uk",
+                    "homepage": "https://github.com/GrahamCampbell"
+                },
                 {
                     "name": "Michael Dowling",
                     "email": "mtdowling@gmail.com",
                     "homepage": "https://github.com/mtdowling"
                 },
+                {
+                    "name": "George Mponos",
+                    "email": "gmponos@gmail.com",
+                    "homepage": "https://github.com/gmponos"
+                },
+                {
+                    "name": "Tobias Nyholm",
+                    "email": "tobias.nyholm@gmail.com",
+                    "homepage": "https://github.com/Nyholm"
+                },
+                {
+                    "name": "Márk Sági-Kazár",
+                    "email": "mark.sagikazar@gmail.com",
+                    "homepage": "https://github.com/sagikazarmark"
+                },
                 {
                     "name": "Tobias Schultze",
+                    "email": "webmaster@tubo-world.de",
                     "homepage": "https://github.com/Tobion"
+                },
+                {
+                    "name": "Márk Sági-Kazár",
+                    "email": "mark.sagikazar@gmail.com",
+                    "homepage": "https://sagikazarmark.hu"
                 }
             ],
             "description": "PSR-7 message implementation that also provides common utility methods",
@@ -309,20 +465,38 @@
                 "uri",
                 "url"
             ],
-            "time": "2020-09-30T07:37:11+00:00"
+            "support": {
+                "issues": "https://github.com/guzzle/psr7/issues",
+                "source": "https://github.com/guzzle/psr7/tree/2.4.4"
+            },
+            "funding": [
+                {
+                    "url": "https://github.com/GrahamCampbell",
+                    "type": "github"
+                },
+                {
+                    "url": "https://github.com/Nyholm",
+                    "type": "github"
+                },
+                {
+                    "url": "https://tidelift.com/funding/github/packagist/guzzlehttp/psr7",
+                    "type": "tidelift"
+                }
+            ],
+            "time": "2023-03-09T13:19:02+00:00"
         },
         {
             "name": "mtdowling/jmespath.php",
-            "version": "2.6.0",
+            "version": "2.6.1",
             "source": {
                 "type": "git",
                 "url": "https://github.com/jmespath/jmespath.php.git",
-                "reference": "42dae2cbd13154083ca6d70099692fef8ca84bfb"
+                "reference": "9b87907a81b87bc76d19a7fb2d61e61486ee9edb"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/jmespath/jmespath.php/zipball/42dae2cbd13154083ca6d70099692fef8ca84bfb",
-                "reference": "42dae2cbd13154083ca6d70099692fef8ca84bfb",
+                "url": "https://api.github.com/repos/jmespath/jmespath.php/zipball/9b87907a81b87bc76d19a7fb2d61e61486ee9edb",
+                "reference": "9b87907a81b87bc76d19a7fb2d61e61486ee9edb",
                 "shasum": ""
             },
             "require": {
@@ -330,7 +504,7 @@
                 "symfony/polyfill-mbstring": "^1.17"
             },
             "require-dev": {
-                "composer/xdebug-handler": "^1.4",
+                "composer/xdebug-handler": "^1.4 || ^2.0",
                 "phpunit/phpunit": "^4.8.36 || ^7.5.15"
             },
             "bin": [
@@ -343,12 +517,12 @@
                 }
             },
             "autoload": {
-                "psr-4": {
-                    "JmesPath\\": "src/"
-                },
                 "files": [
                     "src/JmesPath.php"
-                ]
+                ],
+                "psr-4": {
+                    "JmesPath\\": "src/"
+                }
             },
             "notification-url": "https://packagist.org/downloads/",
             "license": [
@@ -366,7 +540,11 @@
                 "json",
                 "jsonpath"
             ],
-            "time": "2020-07-31T21:01:56+00:00"
+            "support": {
+                "issues": "https://github.com/jmespath/jmespath.php/issues",
+                "source": "https://github.com/jmespath/jmespath.php/tree/2.6.1"
+            },
+            "time": "2021-06-14T00:11:39+00:00"
         },
         {
             "name": "psr/http-client",
@@ -415,24 +593,28 @@
                 "psr",
                 "psr-18"
             ],
+            "support": {
+                "source": "https://github.com/php-fig/http-client/tree/master"
+            },
             "time": "2020-06-29T06:28:15+00:00"
         },
         {
-            "name": "psr/http-message",
+            "name": "psr/http-factory",
             "version": "1.0.1",
             "source": {
                 "type": "git",
-                "url": "https://github.com/php-fig/http-message.git",
-                "reference": "f6561bf28d520154e4b0ec72be95418abe6d9363"
+                "url": "https://github.com/php-fig/http-factory.git",
+                "reference": "12ac7fcd07e5b077433f5f2bee95b3a771bf61be"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/php-fig/http-message/zipball/f6561bf28d520154e4b0ec72be95418abe6d9363",
-                "reference": "f6561bf28d520154e4b0ec72be95418abe6d9363",
+                "url": "https://api.github.com/repos/php-fig/http-factory/zipball/12ac7fcd07e5b077433f5f2bee95b3a771bf61be",
+                "reference": "12ac7fcd07e5b077433f5f2bee95b3a771bf61be",
                 "shasum": ""
             },
             "require": {
-                "php": ">=5.3.0"
+                "php": ">=7.0.0",
+                "psr/http-message": "^1.0"
             },
             "type": "library",
             "extra": {
@@ -455,6 +637,60 @@
                     "homepage": "http://www.php-fig.org/"
                 }
             ],
+            "description": "Common interfaces for PSR-7 HTTP message factories",
+            "keywords": [
+                "factory",
+                "http",
+                "message",
+                "psr",
+                "psr-17",
+                "psr-7",
+                "request",
+                "response"
+            ],
+            "support": {
+                "source": "https://github.com/php-fig/http-factory/tree/master"
+            },
+            "time": "2019-04-30T12:38:16+00:00"
+        },
+        {
+            "name": "psr/http-message",
+            "version": "1.1",
+            "source": {
+                "type": "git",
+                "url": "https://github.com/php-fig/http-message.git",
+                "reference": "cb6ce4845ce34a8ad9e68117c10ee90a29919eba"
+            },
+            "dist": {
+                "type": "zip",
+                "url": "https://api.github.com/repos/php-fig/http-message/zipball/cb6ce4845ce34a8ad9e68117c10ee90a29919eba",
+                "reference": "cb6ce4845ce34a8ad9e68117c10ee90a29919eba",
+                "shasum": ""
+            },
+            "require": {
+                "php": "^7.2 || ^8.0"
+            },
+            "type": "library",
+            "extra": {
+                "branch-alias": {
+                    "dev-master": "1.1.x-dev"
+                }
+            },
+            "autoload": {
+                "psr-4": {
+                    "Psr\\Http\\Message\\": "src/"
+                }
+            },
+            "notification-url": "https://packagist.org/downloads/",
+            "license": [
+                "MIT"
+            ],
+            "authors": [
+                {
+                    "name": "PHP-FIG",
+                    "homepage": "http://www.php-fig.org/"
+                }
+            ],
             "description": "Common interface for HTTP messages",
             "homepage": "https://github.com/php-fig/http-message",
             "keywords": [
@@ -465,7 +701,10 @@
                 "request",
                 "response"
             ],
-            "time": "2016-08-06T14:39:51+00:00"
+            "support": {
+                "source": "https://github.com/php-fig/http-message/tree/1.1"
+            },
+            "time": "2023-04-04T09:50:52+00:00"
         },
         {
             "name": "ralouphie/getallheaders",
@@ -505,32 +744,106 @@
                 }
             ],
             "description": "A polyfill for getallheaders.",
+            "support": {
+                "issues": "https://github.com/ralouphie/getallheaders/issues",
+                "source": "https://github.com/ralouphie/getallheaders/tree/develop"
+            },
             "time": "2019-03-08T08:55:37+00:00"
         },
+        {
+            "name": "symfony/deprecation-contracts",
+            "version": "v3.0.2",
+            "source": {
+                "type": "git",
+                "url": "https://github.com/symfony/deprecation-contracts.git",
+                "reference": "26954b3d62a6c5fd0ea8a2a00c0353a14978d05c"
+            },
+            "dist": {
+                "type": "zip",
+                "url": "https://api.github.com/repos/symfony/deprecation-contracts/zipball/26954b3d62a6c5fd0ea8a2a00c0353a14978d05c",
+                "reference": "26954b3d62a6c5fd0ea8a2a00c0353a14978d05c",
+                "shasum": ""
+            },
+            "require": {
+                "php": ">=8.0.2"
+            },
+            "type": "library",
+            "extra": {
+                "branch-alias": {
+                    "dev-main": "3.0-dev"
+                },
+                "thanks": {
+                    "name": "symfony/contracts",
+                    "url": "https://github.com/symfony/contracts"
+                }
+            },
+            "autoload": {
+                "files": [
+                    "function.php"
+                ]
+            },
+            "notification-url": "https://packagist.org/downloads/",
+            "license": [
+                "MIT"
+            ],
+            "authors": [
+                {
+                    "name": "Nicolas Grekas",
+                    "email": "p@tchwork.com"
+                },
+                {
+                    "name": "Symfony Community",
+                    "homepage": "https://symfony.com/contributors"
+                }
+            ],
+            "description": "A generic function and convention to trigger deprecation notices",
+            "homepage": "https://symfony.com",
+            "support": {
+                "source": "https://github.com/symfony/deprecation-contracts/tree/v3.0.2"
+            },
+            "funding": [
+                {
+                    "url": "https://symfony.com/sponsor",
+                    "type": "custom"
+                },
+                {
+                    "url": "https://github.com/fabpot",
+                    "type": "github"
+                },
+                {
+                    "url": "https://tidelift.com/funding/github/packagist/symfony/symfony",
+                    "type": "tidelift"
+                }
+            ],
+            "time": "2022-01-02T09:55:41+00:00"
+        },
         {
             "name": "symfony/polyfill-mbstring",
-            "version": "v1.22.0",
+            "version": "v1.27.0",
             "source": {
                 "type": "git",
                 "url": "https://github.com/symfony/polyfill-mbstring.git",
-                "reference": "f377a3dd1fde44d37b9831d68dc8dea3ffd28e13"
+                "reference": "8ad114f6b39e2c98a8b0e3bd907732c207c2b534"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/symfony/polyfill-mbstring/zipball/f377a3dd1fde44d37b9831d68dc8dea3ffd28e13",
-                "reference": "f377a3dd1fde44d37b9831d68dc8dea3ffd28e13",
+                "url": "https://api.github.com/repos/symfony/polyfill-mbstring/zipball/8ad114f6b39e2c98a8b0e3bd907732c207c2b534",
+                "reference": "8ad114f6b39e2c98a8b0e3bd907732c207c2b534",
                 "shasum": ""
             },
             "require": {
                 "php": ">=7.1"
             },
+            "provide": {
+                "ext-mbstring": "*"
+            },
             "suggest": {
                 "ext-mbstring": "For best performance"
             },
             "type": "library",
             "extra": {
                 "branch-alias": {
-                    "dev-main": "1.22-dev"
+                    "dev-main": "1.27-dev"
                 },
                 "thanks": {
                     "name": "symfony/polyfill",
@@ -538,12 +851,12 @@
                 }
             },
             "autoload": {
-                "psr-4": {
-                    "Symfony\\Polyfill\\Mbstring\\": ""
-                },
                 "files": [
                     "bootstrap.php"
-                ]
+                ],
+                "psr-4": {
+                    "Symfony\\Polyfill\\Mbstring\\": ""
+                }
             },
             "notification-url": "https://packagist.org/downloads/",
             "license": [
@@ -568,6 +881,9 @@
                 "portable",
                 "shim"
             ],
+            "support": {
+                "source": "https://github.com/symfony/polyfill-mbstring/tree/v1.27.0"
+            },
             "funding": [
                 {
                     "url": "https://symfony.com/sponsor",
@@ -582,7 +898,7 @@
                     "type": "tidelift"
                 }
             ],
-            "time": "2021-01-07T16:49:33+00:00"
+            "time": "2022-11-03T14:55:06+00:00"
         }
     ],
     "packages-dev": [],
@@ -593,5 +909,5 @@
     "prefer-lowest": false,
     "platform": [],
     "platform-dev": [],
-    "plugin-api-version": "1.1.0"
+    "plugin-api-version": "2.3.0"
 }
diff --git a/libraries/Omeka/Storage/Adapter/AmazonS3.php b/libraries/Omeka/Storage/Adapter/AmazonS3.php
index fc9698a..8f5708b 100644
--- a/libraries/Omeka/Storage/Adapter/AmazonS3.php
+++ b/libraries/Omeka/Storage/Adapter/AmazonS3.php
@@ -184,4 +184,20 @@ private function _getAcl()
     {
         return $this->_getExpiration() ? 'private' : 'public-read';
     }
-}
\ No newline at end of file
+
+    /**
+     * Checks if a given object exists
+     *
+     * @param  string $object
+     * @return boolean
+     */
+    public function isObjectAvailable($object)
+    {
+        $response = $this->_s3->headObject([
+          'Bucket' => $this->_getBucket(),
+          'Key' => $object
+        ]);
+
+        return ($response->get('@metadata')['statusCode'] ?? false == 200);
+    }
+}