WP File Download アドオンの競合 / 重大なエラー

WP File Dowload Addonの最新バージョンはSimply Schedule Appointmentsと競合しており、両方を同時に有効にすると重大なエラーが発生します。新しい/lib/prod_vendorフォルダに、古いバージョンのguzzlehttp（6.5.8）が含まれているようです。これは、Simply Schedule Appointmentsに含まれるバージョン7.7.0と競合していると思われます。スタックトレースは以下をご覧ください。

致命的なエラー: キャッチされないエラー: /var/app/current/wp-content/plugins/simply-schedule-appointments/vendor/guzzlehttp/guzzle/src/functions.php:61 で未定義のメソッド GuzzleHttp\Utils::chooseHandler() を呼び出しました スタック トレース: #0 /var/app/current/wp-content/plugins/wp-file-download-cloud-addon/lib/prod_vendor/guzzlehttp/guzzle/src/HandlerStack.php(42): GuzzleHttp\choose_handler() #1 /var/app/current/wp-content/plugins/wp-file-download-cloud-addon/lib/prod_vendor/guzzlehttp/guzzle/src/Client.php(65): GuzzleHttp\HandlerStack::create() #2 /var/app/current/wp-content/plugins/wp-file-download-cloud-addon/lib/prod_vendor/google/apiclient/src/Client.php(1190): GuzzleHttp\Client->__construct(Array) #3 /var/app/current/wp-content/plugins/wp-file-download-cloud-addon/lib/prod_vendor/google/apiclient/src/Client.php(1143): Google\Client->createDefaultHttpClient() #4 /var/app/current/wp-content/plugins/wp-file-download-cloud-addon/lib/prod_vendor/google/apiclient/src/Client.php(411): Google\Client->getHttpClient() #5 /var/app/current/wp-content/plugins/wp-file-download-cloud-addon/lib/prod_vendor/google/apiclient/src/Client.php(891): Google\Client->authorize() #6 /var/app/current/wp-content/plugins/wp-file-download-cloud-addon/lib/prod_vendor/google/apiclient/src/Service/Resource.php(238): Google\Client->execute(Object(GuzzleHttp\Psr7\Request), 'Google\\Service\\...') #7 /var/app/current/wp-content/plugins/wp-file-download-cloud-addon/lib/prod_vendor/google/apiclient-services/src/Drive/Resource/Files.php(174): Google\Service\Resource->call('generateIds', Array, 'Google\\Service\\...') #8 /var/app/current/wp-content/plugins/wp-file-download-cloud-addon/app/admin/classes/WpfdAddonGoogle.php(271): Google\Service\Drive\Resource\Files->generateIds(Array) #9 /var/app/current/wp-content/plugins/wp-file-download-cloud-addon/app/site/google.init.php(14): WpfdAddonGoogleDrive->checkAuth() #10 /var/app/current/wp-content/plugins/wp-file-download-cloud-addon/app/site/init.php(40): include_once('/var/app/curren...') #11 /var/app/current/wp-includes/class-wp-hook.php(308): wpfdAddonInit('') #12 /var/app/current/wp-includes/class-wp-hook.php(332): WP_Hook->apply_filters(NULL, Array) #13 /var/app/current/wp-includes/plugin.php(517): WP_Hook->do_action(Array) #14 /var/app/current/wp-settings.php(623): do_action('init') #15 /var/app/current/wp-config.php(44): require_once('/var/app/curren...') #16 /var/app/current/wp-load.php(50): require_once('/var/app/curren...') #17 /var/app/current/wp-blog-header.php(13): require_once('/var/app/curren...') #18 /var/app/current/index.php(17): require('/var/app/curren...') #19 {main} がスローされました/var/app/current/wp-content/plugins/simply-schedule-appointments/vendor/guzzlehttp/guzzle/src/functions.php の 61 行目