Support » Plugin: Flexible Shipping for FedEx and WooCommerce » critical error when used with cache

  • Resolved paulgros



    I’m seeing an issue with the plugin on a Kinsta hosted site. When cache is disabled the plugin works as expected. With caching enabled then the plugin does not connect to the API and throws a critical error from the basket or checkout page as follows:

    Uncaught Error: Class name must be a valid object or a string in /www/marmotorsportcom_989/public/wp-content/plugins/flexible-shipping-fedex/vendor_prefixed/jeremy-dunn/php-fedex-api-wrapper/src/FedEx/AbstractComplexType.php:160 Stack trace: #0 /www/marmotorsportcom_989/public/wp-content/plugins/flexible-shipping-fedex/vendor_prefixed/jeremy-dunn/php-fedex-api-wrapper/src/FedEx/RateService/Request.php(32): FedExVendor\FedEx\AbstractComplexType->populateFromStdClass(Object(stdClass)) #1 /www/marmotorsportcom_989/public/wp-content/plugins/flexible-shipping-fedex/vendor_prefixed/wpdesk/fedex-shipping-service/src/FedexShippingService/FedexApi/FedexSender.php(89): FedExVendor\FedEx\RateService\Request->getGetRatesReply(Object(FedExVendor\FedEx\RateService\ComplexType\RateRequest)) #2 /www/marmotorsportcom_989/public/wp-content/plugins/flexible-shipping-fedex/vendor_prefixed/wpdesk/fedex-shipping-service/src/FedexShippingService/FedexShippingService.php(132): FedExVendor\WPDesk\FedexShippingService\FedexApi\FedexSe in /www/marmotorsportcom_989/public/wp-content/plugins/flexible-shipping-fedex/vendor_prefixed/jeremy-dunn/php-fedex-api-wrapper/src/FedEx/AbstractComplexType.php on line 160

    The above error was given with all plugins disabled except woocommerce. My host has tried bypassing caching, but still no joy.


    The page I need help with: [log in to see the link]

Viewing 6 replies - 1 through 6 (of 6 total)
  • Hi,
    Same problem here. Just moved to Kinsta yesterday and this problem started. They told me that they use full page Nginx cache. It would be good if you fix the plugin to work properly with this kind of caching.
    For now, I asked them to disable caching in my hosting but this have a big impact to our site performance.

    Plugin Support grzegorzturbasa


    thank you for sharing your problem. The issue that you’re experiencing seems to be connected to the OPCache engine on your server. To make sure that our plugin works correctly – and get rid of the given error – please disable directive. You can read more about it here:

    I hope that provided solution will be helpful.

    Kind Regards,


    I’ve asked Kinsta support team and they tell me that the opcache_save.comments is set to 0 on Kinsta live environments.

    Is there any other thing we can check?


    Plugin Contributor Grzegorz Rola



    it should be set to 1, which means: disable discarding comments from code.

    Best regards

    Plugin Support Marta Pawlonka


    As we haven’t got any replies, I’m marking this topic as resolved for now.



    Sorry, I forgot to confirm that the issue is fixed now.
    Thanks for your support!

Viewing 6 replies - 1 through 6 (of 6 total)
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