Fatal error: Uncaught Error: Undefined constant GuzzleHttp\ClientInterface:

I was trying to find a plugin to migrate my site from my localhost (xampp) to my online domain. After trying several my WP crashed and I got the following message:

Fatal error: Uncaught Error: Undefined constant GuzzleHttp\ClientInterface::MAJOR_VERSION in D:\Websites\Wordpress_Sites\XAMPP\htdocs\paulbohannaceramics\wordpress\wp-content\plugins\pymntpl-paypal-woocommerce\vendor\guzzlehttp\guzzle\src\Utils.php:116 Stack trace: #0 D:\Websites\Wordpress_Sites\XAMPP\htdocs\paulbohannaceramics\wordpress\wp-content\plugins\pymntpl-paypal-woocommerce\vendor\guzzlehttp\guzzle\src\functions.php(71): GuzzleHttp\Utils::defaultUserAgent() #1 D:\Websites\Wordpress_Sites\XAMPP\htdocs\paulbohannaceramics\wordpress\wp-content\plugins\wp-migration-duplicator\admin\vendor\guzzlehttp\guzzle\src\Client.php(278): GuzzleHttp\default_user_agent() #2 D:\Websites\Wordpress_Sites\XAMPP\htdocs\paulbohannaceramics\wordpress\wp-content\plugins\wp-migration-duplicator\admin\vendor\guzzlehttp\guzzle\src\Client.php(76): GuzzleHttp\Client->configureDefaults(Array) #3 D:\Websites\Wordpress_Sites\XAMPP\htdocs\paulbohannaceramics\wordpress\wp-content\plugins\pymntpl-paypal-woocommerce\vendor\paymentplugins\paypal-php-sdk\src\Client\BaseHttpClient.php(40): GuzzleHttp\Client->__construct(Array) #4 D:\Websites\Wordpress_Sites\XAMPP\htdocs\paulbohannaceramics\wordpress\wp-content\plugins\pymntpl-paypal-woocommerce\src\WPPayPalClient.php(45): PaymentPlugins\PayPalSDK\Client\BaseHttpClient->__construct(Array) #5 D:\Websites\Wordpress_Sites\XAMPP\htdocs\paulbohannaceramics\wordpress\wp-content\plugins\pymntpl-paypal-woocommerce\src\Main.php(143): PaymentPlugins\WooCommerce\PPCP\WPPayPalClient->__construct(Object(PaymentPlugins\WooCommerce\PPCP\Admin\Settings\APISettings), Object(PaymentPlugins\WooCommerce\PPCP\Logger)) #6 D:\Websites\Wordpress_Sites\XAMPP\htdocs\paulbohannaceramics\wordpress\wp-content\plugins\pymntpl-paypal-woocommerce\src\Container\AbstractResolver.php(18): PaymentPlugins\WooCommerce\PPCP\Main->PaymentPlugins\WooCommerce\PPCP\{closure}(Object(PaymentPlugins\WooCommerce\PPCP\Container\Container)) #7 D:\Websites\Wordpress_Sites\XAMPP\htdocs\paulbohannaceramics\wordpress\wp-content\plugins\pymntpl-paypal-woocommerce\src\Container\BaseResolver.php(13): PaymentPlugins\WooCommerce\PPCP\Container\AbstractResolver->resolve(Object(PaymentPlugins\WooCommerce\PPCP\Container\Container)) #8 D:\Websites\Wordpress_Sites\XAMPP\htdocs\paulbohannaceramics\wordpress\wp-content\plugins\pymntpl-paypal-woocommerce\src\Container\Container.php(25): PaymentPlugins\WooCommerce\PPCP\Container\BaseResolver->get(Object(PaymentPlugins\WooCommerce\PPCP\Container\Container)) #9 D:\Websites\Wordpress_Sites\XAMPP\htdocs\paulbohannaceramics\wordpress\wp-content\plugins\pymntpl-paypal-woocommerce\src\Rest\RestController.php(47): PaymentPlugins\WooCommerce\PPCP\Container\Container->get('PaymentPlugins\\...') #10 D:\Websites\Wordpress_Sites\XAMPP\htdocs\paulbohannaceramics\wordpress\wp-content\plugins\pymntpl-paypal-woocommerce\src\Rest\RestController.php(42): PaymentPlugins\WooCommerce\PPCP\Rest\RestController->initialize() #11 D:\Websites\Wordpress_Sites\XAMPP\htdocs\paulbohannaceramics\wordpress\wp-content\plugins\pymntpl-paypal-woocommerce\src\Main.php(179): PaymentPlugins\WooCommerce\PPCP\Rest\RestController->__construct(Object(PaymentPlugins\WooCommerce\PPCP\Container\Container)) #12 D:\Websites\Wordpress_Sites\XAMPP\htdocs\paulbohannaceramics\wordpress\wp-content\plugins\pymntpl-paypal-woocommerce\src\Container\AbstractResolver.php(18): PaymentPlugins\WooCommerce\PPCP\Main->PaymentPlugins\WooCommerce\PPCP\{closure}(Object(PaymentPlugins\WooCommerce\PPCP\Container\Container)) #13 D:\Websites\Wordpress_Sites\XAMPP\htdocs\paulbohannaceramics\wordpress\wp-content\plugins\pymntpl-paypal-woocommerce\src\Container\BaseResolver.php(13): PaymentPlugins\WooCommerce\PPCP\Container\AbstractResolver->resolve(Object(PaymentPlugins\WooCommerce\PPCP\Container\Container)) #14 D:\Websites\Wordpress_Sites\XAMPP\htdocs\paulbohannaceramics\wordpress\wp-content\plugins\pymntpl-paypal-woocommerce\src\Container\Container.php(25): PaymentPlugins\WooCommerce\PPCP\Container\BaseResolver->get(Object(PaymentPlugins\WooCommerce\PPCP\Container\Container)) #15 D:\Websites\Wordpress_Sites\XAMPP\htdocs\paulbohannaceramics\wordpress\wp-content\plugins\pymntpl-paypal-woocommerce\packages\blocks\src\Package.php(43): PaymentPlugins\WooCommerce\PPCP\Container\Container->get('PaymentPlugins\\...') #16 D:\Websites\Wordpress_Sites\XAMPP\htdocs\paulbohannaceramics\wordpress\wp-content\plugins\pymntpl-paypal-woocommerce\src\Container\AbstractResolver.php(18): PaymentPlugins\PPCP\Blocks\Package->PaymentPlugins\PPCP\Blocks\{closure}(Object(PaymentPlugins\WooCommerce\PPCP\Container\Container)) #17 D:\Websites\Wordpress_Sites\XAMPP\htdocs\paulbohannaceramics\wordpress\wp-content\plugins\pymntpl-paypal-woocommerce\src\Container\BaseResolver.php(13): PaymentPlugins\WooCommerce\PPCP\Container\AbstractResolver->resolve(Object(PaymentPlugins\WooCommerce\PPCP\Container\Container)) #18 D:\Websites\Wordpress_Sites\XAMPP\htdocs\paulbohannaceramics\wordpress\wp-content\plugins\pymntpl-paypal-woocommerce\src\Container\Container.php(25): PaymentPlugins\WooCommerce\PPCP\Container\BaseResolver->get(Object(PaymentPlugins\WooCommerce\PPCP\Container\Container)) #19 D:\Websites\Wordpress_Sites\XAMPP\htdocs\paulbohannaceramics\wordpress\wp-content\plugins\pymntpl-paypal-woocommerce\packages\blocks\src\Package.php(75): PaymentPlugins\WooCommerce\PPCP\Container\Container->get('PaymentPlugins\\...') #20 D:\Websites\Wordpress_Sites\XAMPP\htdocs\paulbohannaceramics\wordpress\wp-content\plugins\pymntpl-paypal-woocommerce\src\Package\PackageController.php(50): PaymentPlugins\PPCP\Blocks\Package->initialize() #21 D:\Websites\Wordpress_Sites\XAMPP\htdocs\paulbohannaceramics\wordpress\wp-includes\class-wp-hook.php(308): PaymentPlugins\WooCommerce\PPCP\Package\PackageController->initialize_packages('') #22 D:\Websites\Wordpress_Sites\XAMPP\htdocs\paulbohannaceramics\wordpress\wp-includes\class-wp-hook.php(332): WP_Hook->apply_filters(NULL, Array) #23 D:\Websites\Wordpress_Sites\XAMPP\htdocs\paulbohannaceramics\wordpress\wp-includes\plugin.php(517): WP_Hook->do_action(Array) #24 D:\Websites\Wordpress_Sites\XAMPP\htdocs\paulbohannaceramics\wordpress\wp-content\plugins\woocommerce\includes\class-woocommerce.php(667): do_action('woocommerce_ini...') #25 D:\Websites\Wordpress_Sites\XAMPP\htdocs\paulbohannaceramics\wordpress\wp-includes\class-wp-hook.php(308): WooCommerce->init('') #26 D:\Websites\Wordpress_Sites\XAMPP\htdocs\paulbohannaceramics\wordpress\wp-includes\class-wp-hook.php(332): WP_Hook->apply_filters(NULL, Array) #27 D:\Websites\Wordpress_Sites\XAMPP\htdocs\paulbohannaceramics\wordpress\wp-includes\plugin.php(517): WP_Hook->do_action(Array) #28 D:\Websites\Wordpress_Sites\XAMPP\htdocs\paulbohannaceramics\wordpress\wp-settings.php(617): do_action('init') #29 D:\Websites\Wordpress_Sites\XAMPP\htdocs\paulbohannaceramics\wordpress\wp-config.php(96): require_once('D:\\Websites\\Wor...') #30 D:\Websites\Wordpress_Sites\XAMPP\htdocs\paulbohannaceramics\wordpress\wp-load.php(50): require_once('D:\\Websites\\Wor...') #31 D:\Websites\Wordpress_Sites\XAMPP\htdocs\paulbohannaceramics\wordpress\wp-admin\admin.php(34): require_once('D:\\Websites\\Wor...') #32 D:\Websites\Wordpress_Sites\XAMPP\htdocs\paulbohannaceramics\wordpress\wp-admin\plugin-install.php(16): require_once('D:\\Websites\\Wor...') #33 {main} thrown in D:\Websites\Wordpress_Sites\XAMPP\htdocs\paulbohannaceramics\wordpress\wp-content\plugins\pymntpl-paypal-woocommerce\vendor\guzzlehttp\guzzle\src\Utils.php on line 116

I am now unable to access anything except the message above. I have no idea what to do. Please help. Thank you.