Title: E_ERROR Cannot declare interface AcVendor\Psr\Http\Client\ClientInterface Last modified: August 17, 2023 --- # E_ERROR Cannot declare interface AcVendor\Psr\Http\Client\ClientInterface * Resolved [bluesix](https://wordpress.org/support/users/bluesix/) * (@bluesix) * [2 years, 9 months ago](https://wordpress.org/support/topic/e_error-cannot-declare-interface-acvendorpsrhttpclientclientinterface/) * Hi, my client is receiving this fatal error today with: - AC for WC 2.4.1 - WP 6.3 - WC 8.0.2 * Error Details =============An error of type E_ERROR was caused in line 7 of the file /wp-content/plugins/activecampaign-for-woocommerce/ac_vendor/psr/http-client/ src/ClientInterface.php. Error message: Cannot declare interface AcVendor\Psr\ Http\Client\ClientInterface, because the name is already in use * Please let me know what we should do. Viewing 8 replies - 1 through 8 (of 8 total) * [unitcpro](https://wordpress.org/support/users/unitcpro/) * (@unitcpro) * [2 years, 9 months ago](https://wordpress.org/support/topic/e_error-cannot-declare-interface-acvendorpsrhttpclientclientinterface/#post-16995505) * Error: Cannot declare interface AcVendor\Psr\Http\Message\RequestFactoryInterface, because the name is already in use in /var/www/wp-content/plugins/activecampaign- for-woocommerce_old/ac_vendor/psr/http-factory/src/RequestFactoryInterface.php on line 5 * We have the same problem with the plugin, how we should proceed is urgent since the customer flow is not being registered by ActiveCampaing. thank you. * Plugin Author [ActiveCampaign](https://wordpress.org/support/users/acteamintegrations/) * (@acteamintegrations) * [2 years, 9 months ago](https://wordpress.org/support/topic/e_error-cannot-declare-interface-acvendorpsrhttpclientclientinterface/#post-17001448) * [@unitcpro](https://wordpress.org/support/users/unitcpro/) Do you happen to have a vendor folder in the activecampaign-for-woocommerce plugin folder? It would be `activecampaign-for-woocommerce/vendor` If so you may want to delete that directory or overwrite the plugin and reinstall it. You shouldn’t need to delete it, just install again over the old one. * [@bluesix](https://wordpress.org/support/users/bluesix/) Is this on a specific page, performing a specific action or a global error when the plugin is active? Do you happen to know which page it’s in conflict with? Does the suggestion above resolve your issue? * It looks like you’re both seeing ac_vendor file errors but they are different errors. This kind of error usually only happens with a conflict so it might be that the version update didn’t properly remove the conflicting vendor directory. * Thread Starter [bluesix](https://wordpress.org/support/users/bluesix/) * (@bluesix) * [2 years, 9 months ago](https://wordpress.org/support/topic/e_error-cannot-declare-interface-acvendorpsrhttpclientclientinterface/#post-17002129) * With the plugin active, the entire site crashes – it’s a global fatal error. * I do not have a `vendor` folder in the plugin. There is an `ac_vendor` folder though (which I can also see in SVN, so it should be there). * Deleting the plugin folder and reinstalling hasn’t helped. * FWIW, activecampaign-subscription-forms and activemember360 plugins are also installed. I’m guessing that’s why the “Cannot declare interface AcVendor\Psr\ Http\Client\ClientInterface, because the name is already in use” error is ocurring. - This reply was modified 2 years, 9 months ago by [bluesix](https://wordpress.org/support/users/bluesix/). * [unitcpro](https://wordpress.org/support/users/unitcpro/) * (@unitcpro) * [2 years, 9 months ago](https://wordpress.org/support/topic/e_error-cannot-declare-interface-acvendorpsrhttpclientclientinterface/#post-17007471) * try these two things - Locate the ac_vendor folder, replace it, it didn’t work. - Remove the plugin completely, check that there is no trace of the previous installation in the plugin folder and I did a clean install and it didn’t work. * This solution did not work for me. the error occurs when activating the plugin. * [dnesbit](https://wordpress.org/support/users/dnesbit/) * (@dnesbit) * [2 years, 9 months ago](https://wordpress.org/support/topic/e_error-cannot-declare-interface-acvendorpsrhttpclientclientinterface/#post-17008185) * Fatal site error caused by Version 2.4.1 | Site crashes when this plugin is activated( 8/28/23). Downloaded fresh copy of plugin and installed, with same result. * An error of type E_ERROR was caused in line 5 of the file /var/www/wp-content/ plugins/activecampaign-for-woocommerce/ac_vendor/psr/http-factory/src/RequestFactoryInterface. php. Error message: Cannot declare interface AcVendor\Psr\Http\Message\RequestFactoryInterface, because the name is already in use * This plugin failed to load properly and is paused during recovery mode. * Plugin Author [ActiveCampaign](https://wordpress.org/support/users/acteamintegrations/) * (@acteamintegrations) * [2 years, 9 months ago](https://wordpress.org/support/topic/e_error-cannot-declare-interface-acvendorpsrhttpclientclientinterface/#post-17016237) * We’ve been trying to reproduce this on multiple versions of PHP and with older versions of WooCommerce but we’re not seeing this error come up. Is there any more information that any of you can share such as maybe another plugin is conflicting or possibly the other place the interface is being loaded? * It may be caused by one of our vendor packages. I doubt version 2.4.2 fixes this issue but if it does please let us know. We’ll try to investigate further. * Thread Starter [bluesix](https://wordpress.org/support/users/bluesix/) * (@bluesix) * [2 years, 9 months ago](https://wordpress.org/support/topic/e_error-cannot-declare-interface-acvendorpsrhttpclientclientinterface/#post-17017108) * The problem appears to be fixed with 2.4.2. Thank you! * Plugin Author [ActiveCampaign](https://wordpress.org/support/users/acteamintegrations/) * (@acteamintegrations) * [2 years, 9 months ago](https://wordpress.org/support/topic/e_error-cannot-declare-interface-acvendorpsrhttpclientclientinterface/#post-17019265) * That’s great to hear. It could have been a build issue or something to do with how plugins are posted to WP. We were about to try updating all of the composer packages we use but we’re hoping it’s fixed for everyone. Rather be cautious to make sure it’s as compatible as possible for anyone who installs than move forward with changes. * If anyone else is still facing this issue please update the ticket and we’ll take another look. Viewing 8 replies - 1 through 8 (of 8 total) The topic ‘E_ERROR Cannot declare interface AcVendor\Psr\Http\Client\ClientInterface’ is closed to new replies. * ![](https://ps.w.org/activecampaign-for-woocommerce/assets/icon-256x256.png?rev =1925389) * [ActiveCampaign for WooCommerce](https://wordpress.org/plugins/activecampaign-for-woocommerce/) * [Support Threads](https://wordpress.org/support/plugin/activecampaign-for-woocommerce/) * [Active Topics](https://wordpress.org/support/plugin/activecampaign-for-woocommerce/active/) * [Unresolved Topics](https://wordpress.org/support/plugin/activecampaign-for-woocommerce/unresolved/) * [Reviews](https://wordpress.org/support/plugin/activecampaign-for-woocommerce/reviews/) * 8 replies * 4 participants * Last reply from: [ActiveCampaign](https://wordpress.org/support/users/acteamintegrations/) * Last activity: [2 years, 9 months ago](https://wordpress.org/support/topic/e_error-cannot-declare-interface-acvendorpsrhttpclientclientinterface/#post-17019265) * Status: resolved