Title: Undefined class constant ‘VERSION’ Last modified: October 21, 2020 --- # Undefined class constant ‘VERSION’ * Resolved [alexislevrai](https://wordpress.org/support/users/alexislevrai/) * (@alexislevrai) * [5 years, 7 months ago](https://wordpress.org/support/topic/undefined-class-constant-version-2/) * Hello, * After updating Mollie for WP I facing an error when I add a product in cart : * Fatal error: Uncaught Error: Undefined class constant ‘VERSION’ in /homepages/ wordpress/wp-content/plugins/mollie-payments-for-woocommerce-aaa/vendor/mollie/ mollie-api-php/src/MollieApiClient.php:287 Stack trace: #0 /homepages/wordpress/ wp-content/plugins/mollie-payments-for-woocommerce-aaa/src/Mollie/WC/Helper/Api. php(45): Mollie\Api\MollieApiClient->__construct() #1 /homepages/wordpress/wp- content/plugins/mollie-payments-for-woocommerce-aaa/src/Mollie/WC/Helper/Data. php(341): Mollie_WC_Helper_Api->getApiClient(true) #2 /homepages/wordpress/wp- content/plugins/mollie-payments-for-woocommerce-aaa/src/Mollie/WC/Gateway/Abstract. php(2143): Mollie_WC_Helper_Data->getApiPaymentMethods(true, true, Array) #3 / homepages/wordpress/wp-content/plugins/mollie-payments-for-woocommerce-aaa/src/ Mollie/WC/Gateway/Abstract.php(319): Mollie_WC_Gateway_Abstract->isAvailable in /homepages/wordpress/wp-content/plugins/mollie-payments-for-woocommerce-aaa/ vendor/mollie/mollie-api-php/src/MollieApiClient.php on line 287 Viewing 15 replies - 1 through 15 (of 20 total) 1 [2](https://wordpress.org/support/topic/undefined-class-constant-version-2/page/2/?output_format=md) [→](https://wordpress.org/support/topic/undefined-class-constant-version-2/page/2/?output_format=md) * Plugin Support [Syde Niklas](https://wordpress.org/support/users/niklasinpsyde/) * (@niklasinpsyde) * [5 years, 7 months ago](https://wordpress.org/support/topic/undefined-class-constant-version-2/#post-13561107) * Hey there [@alexislevrai](https://wordpress.org/support/users/alexislevrai/) , * The issue is a version conflict between the library GuzzleHttp version 6 and 7. We found that one plugin potentially causing this conflict was WooCommerce Bookings. Our plugin will soon be updated to prevent dependency conflicts like this in the future. * In the meantime, we have received reports that mollie 5.8.3. works well with the most recent WooCommerce Bookings version. Please let me know if this works for you as well. * Kind regards, Niklas * Thread Starter [alexislevrai](https://wordpress.org/support/users/alexislevrai/) * (@alexislevrai) * [5 years, 7 months ago](https://wordpress.org/support/topic/undefined-class-constant-version-2/#post-13561139) * Hi [@niklasinpsyde](https://wordpress.org/support/users/niklasinpsyde/) * Right, I’m using woocommerce booking. So I’m happy to read that you are already informed about this bug, and that the problem don’t come from me 😝 * So I will wait for the next update, the bug appeared on the pre-production website so I can wait. * Thank you for your quick reply ! Alexis * [mediablocks](https://wordpress.org/support/users/mediablocks/) * (@mediablocks) * [5 years, 7 months ago](https://wordpress.org/support/topic/undefined-class-constant-version-2/#post-13571570) * Hello, * Here the same issue and 5.8.3 is not working in my case. * If there a fast solution possible? * Regards, Alex * Plugin Support [Syde Niklas](https://wordpress.org/support/users/niklasinpsyde/) * (@niklasinpsyde) * [5 years, 7 months ago](https://wordpress.org/support/topic/undefined-class-constant-version-2/#post-13571596) * Hello [@mediablocks](https://wordpress.org/support/users/mediablocks/), * We are working to resolve this issue. But since we will implement this change into a variety of plugins, it will take a little bit more time for our final implementation. * In the meantime we have created a test package which you can [download here](https://drive.google.com/file/d/1f3oZxRQNTju3ehzHe65IngLkdrnvo86y/view?usp=sharing). The download link will be removed once our new implementation is released. Before you install the package, please create a site backup. We have received reports that for some customers this test package resolved all issues, but for others some issues remained. * I will keep all threads realting to this issue updated with our progress. Thanks for letting us know. * Kind regards, Niklas * [mediablocks](https://wordpress.org/support/users/mediablocks/) * (@mediablocks) * [5 years, 7 months ago](https://wordpress.org/support/topic/undefined-class-constant-version-2/#post-13571712) * Hello, * This one is working voor me. * Regards, Alex * [eduxpw](https://wordpress.org/support/users/eduxpw/) * (@eduxpw) * [5 years, 7 months ago](https://wordpress.org/support/topic/undefined-class-constant-version-2/#post-13597403) * Hi ! * I have the same problem but your fix doesn’t work for me :/ Do you have another fix, or another way to fix this error ? * Thanks, * Plugin Support [Syde Niklas](https://wordpress.org/support/users/niklasinpsyde/) * (@niklasinpsyde) * [5 years, 7 months ago](https://wordpress.org/support/topic/undefined-class-constant-version-2/#post-13600566) * Hello [@eduxpw](https://wordpress.org/support/users/eduxpw/), * I’m sorry to hear that neither a downgrade to Mollie version 5.8.3 nor our test package could solve the issue in your case. Can your please also try to downgrade WooCommerce Subscriptions to version 1.15.21? We have received multiple reports that this version works well with Mollie 5.8.3. Please let me know if this helps. * We are currently preparing our next release which is planned for early next week. Since this issue is more complex than anticipated, we were not able to include our final implementation in this next update and will push it as an additional update later on. So for now and a short period after our next update, we still recommend using Mollie 5.8.3 if you rely on Subscriptions. * Kind regards, Niklas * [michaellammers](https://wordpress.org/support/users/michaellammers/) * (@michaellammers) * [5 years, 7 months ago](https://wordpress.org/support/topic/undefined-class-constant-version-2/#post-13614883) * Update unfortunately didn’t fix the problem… I still have this error with configuration: – Woocommerce Bookings 1.15.29 – Mollie-betalingen voor WooCommerce 5.10.0 * Plugin Support [Syde Niklas](https://wordpress.org/support/users/niklasinpsyde/) * (@niklasinpsyde) * [5 years, 7 months ago](https://wordpress.org/support/topic/undefined-class-constant-version-2/#post-13615034) * Hi [@michaellammers](https://wordpress.org/support/users/michaellammers/), * Our new release version 5.10.0 does not include a fix for the conflict with Bookings yet. The fix will be included in our next update. In the meantime we still recommend using either Mollie 5.8.3 or the test package I have linked in my earlier message if you rely on WooCommerce Bookings. I will keep all related threads updated as soon as we have a better solution. Thanks! * Kind regards, Niklas * [michaellammers](https://wordpress.org/support/users/michaellammers/) * (@michaellammers) * [5 years, 7 months ago](https://wordpress.org/support/topic/undefined-class-constant-version-2/#post-13625564) * Thanks [@niklasinpsyde](https://wordpress.org/support/users/niklasinpsyde/). Quick update: Have once again tried with 5.8.3. version, but unfortunately it crashes with the same error. Hope for solution soon, since the current working config has older plugins which is a potential security risk. Thanks so far, will check here regularly. ✌️ * [michaellammers](https://wordpress.org/support/users/michaellammers/) * (@michaellammers) * [5 years, 6 months ago](https://wordpress.org/support/topic/undefined-class-constant-version-2/#post-13654928) * I’ve noticed an update to 5.11.0. Does this fix the issue [@niklasinpsyde](https://wordpress.org/support/users/niklasinpsyde/)? I wanted to check first since it’s not mentioned (as far as I can see). * [loekzanders](https://wordpress.org/support/users/loekzanders/) * (@loekzanders) * [5 years, 6 months ago](https://wordpress.org/support/topic/undefined-class-constant-version-2/#post-13708025) * Hi both! * Unfortunately, I am experiencing the same issue. I checked in with the helpdesk at WC already, but they are redirecting me to you/Mollie. * Relevant plug-ins I am working with are: * ### Active Plugins (29) ### Mollie Payments for WooCommerce: by Mollie – 5.11.0 Checkout Field Editor for WooCommerce: by ThemeHigh – 1.4.4 WooCommerce Bookings: by WooCommerce – 1.15.27 WooCommerce Multilingual: by OnTheGoSystems – 4.10.3 WooCommerce PDF Invoices & Packing Slips: by Ewout Fernhout – 2.7.2 WooCommerce: by Automattic – 4.7.1 * Looking forward to an update! * Plugin Support [Syde Niklas](https://wordpress.org/support/users/niklasinpsyde/) * (@niklasinpsyde) * [5 years, 6 months ago](https://wordpress.org/support/topic/undefined-class-constant-version-2/#post-13708293) * Hi [@michaellammers](https://wordpress.org/support/users/michaellammers/) & [@loekzanders](https://wordpress.org/support/users/loekzanders/), * Unfortunately this issue is very complex to solve, that’s why the latest version 5.11.0 does not yet include a fix for the issue. Our next version is scheduled for sometime early december and we hope to be able to include the fix for this issue with it. We are making good progress but had a couple of setbacks, that’s why it’s taking so long. But we are commited to resolve this once and for all. * Mollie 5.8.3 should work in combination with WooCommerce Bookings 1.15.21 if you are still experiencing the issue with the package I have provided in this thread. As I have said before, I will update all related threads, once we have a solution ready for you. Thank you so much for bearing with us! * Kind regards, Niklas * Plugin Support [Syde Niklas](https://wordpress.org/support/users/niklasinpsyde/) * (@niklasinpsyde) * [5 years, 6 months ago](https://wordpress.org/support/topic/undefined-class-constant-version-2/#post-13712923) * Hello [@alexislevrai](https://wordpress.org/support/users/alexislevrai/), [@mediablocks](https://wordpress.org/support/users/mediablocks/), [@eduxpw](https://wordpress.org/support/users/eduxpw/), [@michaellammers](https://wordpress.org/support/users/michaellammers/)& [@loekzanders](https://wordpress.org/support/users/loekzanders/) * Thank you so much for your patience regarding this issue. We have created a new Mollie version, which should resolve this issue for now. The core problematic is very complex to solve for good, that means this fix is not yet our final implementation and we will continue to work on it. But at least, it should work properly for now. 🙂 * Please download the new Mollie version from this link here and give it a try: [https://drive.google.com/file/d/1uUQx7I9UYodGKxRzAyeS40znL0Ru04ox/view?usp=sharing](https://drive.google.com/file/d/1uUQx7I9UYodGKxRzAyeS40znL0Ru04ox/view?usp=sharing) * So far, our internal tests with WooCommerce Bookings and Simple Calender were successful. But we of course appreciate your feedback regarding this fix, so we can potentially include it in our next regular update in the first half of december, in case we cannot get our final implementation done in time. Thank you so much! * Kind regards, Niklas * Thread Starter [alexislevrai](https://wordpress.org/support/users/alexislevrai/) * (@alexislevrai) * [5 years, 6 months ago](https://wordpress.org/support/topic/undefined-class-constant-version-2/#post-13712961) * [@niklasinpsyde](https://wordpress.org/support/users/niklasinpsyde/) * Thanks for the update ! I prefer to wait for the final fix 🙂 Can you please notify us when it will be shipped ? * ++ Viewing 15 replies - 1 through 15 (of 20 total) 1 [2](https://wordpress.org/support/topic/undefined-class-constant-version-2/page/2/?output_format=md) [→](https://wordpress.org/support/topic/undefined-class-constant-version-2/page/2/?output_format=md) The topic ‘Undefined class constant ‘VERSION’’ is closed to new replies. * ![](https://ps.w.org/mollie-payments-for-woocommerce/assets/icon-256x256.png? rev=3090580) * [Mollie Payments for WooCommerce](https://wordpress.org/plugins/mollie-payments-for-woocommerce/) * [Frequently Asked Questions](https://wordpress.org/plugins/mollie-payments-for-woocommerce/#faq) * [Support Threads](https://wordpress.org/support/plugin/mollie-payments-for-woocommerce/) * [Active Topics](https://wordpress.org/support/plugin/mollie-payments-for-woocommerce/active/) * [Unresolved Topics](https://wordpress.org/support/plugin/mollie-payments-for-woocommerce/unresolved/) * [Reviews](https://wordpress.org/support/plugin/mollie-payments-for-woocommerce/reviews/) * 20 replies * 6 participants * Last reply from: [alexislevrai](https://wordpress.org/support/users/alexislevrai/) * Last activity: [5 years, 5 months ago](https://wordpress.org/support/topic/undefined-class-constant-version-2/page/2/#post-13821462) * Status: resolved