Title: Zettle plugin when activated causing WordPress critical error
Last modified: June 8, 2023

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# Zettle plugin when activated causing WordPress critical error

 *  Resolved [mattphillips](https://wordpress.org/support/users/mattphillips/)
 * (@mattphillips)
 * [3 years ago](https://wordpress.org/support/topic/zettle-plugin-when-activated-causing-wordpress-critical-error/)
 * Hello! We have our WooCommerce WordPress site hosted by Ionos. Today, out of 
   nowhere, the site became inaccessible and stated “There Has Been a Critical Error
   on This Website”.
 * I contacted Ionos support via live chat and they were able to deactivate the 
   Zettle POS plugin, which they said is what was causing the critical error on 
   my website. Here is the plugin fatal error Ionos provided me:
   wp plugin activate
   zettle-pos-integrationFatal error: Declaration of Inpsyde\Wp\HttpClient\Client::
   sendRequest(Psr\Http\Message\RequestInterface $request): Psr\Http\Message\ResponseInterface
   must be compatible with Psr\Http\Client\ClientInterface::sendRequest(Automattic\
   WooCommerce\GoogleListingsAndAds\Vendor\Psr\Http\Message\RequestInterface $request):
   Automattic\WooCommerce\GoogleListingsAndAds\Vendor\Psr\Http\Message\ResponseInterface
   in /homepages/36/d4297208015/htdocs/wordpress/wp-content/plugins/zettle-pos-integration/
   vendor/inpsyde/psr-18-wp-http-client/src/Client.php on line 77
 * Ionos indicated that this is an error in running a wpcli command in activating
   a plugin. It appears there are compatibility issues with the plugin or themes
   or version of WordPress. Ask them if there are any other requirements they need
   to make sure the plugin works for our site.
 * Any help with this would be greatly appreciated!

Viewing 2 replies - 1 through 2 (of 2 total)

 *  Plugin Support [Syde Joost](https://wordpress.org/support/users/joostvandevijver/)
 * (@joostvandevijver)
 * [2 years, 12 months ago](https://wordpress.org/support/topic/zettle-plugin-when-activated-causing-wordpress-critical-error/#post-16805971)
 * Hello [@mattphillips](https://wordpress.org/support/users/mattphillips/)
 * Thank you for reaching out to us, we are here to help.
 * I discussed this with our lead developer, and we believe this is a conflict with
   another plugin (WC Google Listings & Ads) and is caused because it loads a different
   version of the same library or actually maybe not version.
 * It seems like this plugin tried to prefix its libraries to avoid such conflicts,
   but they did it only for part of the PSR HTTP-related interfaces, making it worse
   when they use each the other one. This is why this issue should most likely be
   report to [**WooCommerce** **Google Listings & Ads**](https://wordpress.org/plugins/google-listings-and-ads/#developers).
   
   Also, you should probably check what version you are using of this plugin. If
   you are using the latest version, then downgrading to 2.4.7 should help for now.
   Here is the link to this site: [https://wordpress.org/plugins/google-listings-and-ads/#developers](https://wordpress.org/plugins/google-listings-and-ads/#developers)
 * Let me know if this helped you resolve the issue for now.
 * Kind regards,
   Joost
 *  Plugin Support [Syde Joost](https://wordpress.org/support/users/joostvandevijver/)
 * (@joostvandevijver)
 * [2 years, 11 months ago](https://wordpress.org/support/topic/zettle-plugin-when-activated-causing-wordpress-critical-error/#post-16836528)
 * Hello,
 * Since we did not receive any response or follow-up questions from you, we will
   assume you got this working to your requirements. If you still have any more 
   questions for us, please open a new thread, because we will mark this one as 
   resolved.
 * Kind regards,
   Joost

Viewing 2 replies - 1 through 2 (of 2 total)

The topic ‘Zettle plugin when activated causing WordPress critical error’ is closed
to new replies.

 * ![](https://ps.w.org/zettle-pos-integration/assets/icon-256x256.png?rev=2694076)
 * [PayPal Zettle POS for WooCommerce](https://wordpress.org/plugins/zettle-pos-integration/)
 * [Frequently Asked Questions](https://wordpress.org/plugins/zettle-pos-integration/#faq)
 * [Support Threads](https://wordpress.org/support/plugin/zettle-pos-integration/)
 * [Active Topics](https://wordpress.org/support/plugin/zettle-pos-integration/active/)
 * [Unresolved Topics](https://wordpress.org/support/plugin/zettle-pos-integration/unresolved/)
 * [Reviews](https://wordpress.org/support/plugin/zettle-pos-integration/reviews/)

 * 2 replies
 * 2 participants
 * Last reply from: [Syde Joost](https://wordpress.org/support/users/joostvandevijver/)
 * Last activity: [2 years, 11 months ago](https://wordpress.org/support/topic/zettle-plugin-when-activated-causing-wordpress-critical-error/#post-16836528)
 * Status: resolved