Fatal error when enabling Multi currency - Compatibility with third party plugin

[marcusig]

ℹ This is a duplicate of this thread, as it's more likely to get an answer from a developer here.

Hi there,

I’m the author of the plugin Product Configurator for WooCommerce

Since version 9.1.0, accessing the cart page with a configurable product (Additional options added by the above plugin) in the cart triggers a fatal error (memory exhausted).

I also noticed a slight increase in load time on the cart with regular products, but nothing breaking.

This can be observed on this test site: https://demos.mklacroix.com/monpetitmagasin/

I’m trying to find out what could be the cause of that issue. Would anyone be able to tell me significant changes in the Multi Currency feature between 9.0 and 9.1?

A user reported this error:

Error 'PHP message: PHP Fatal error: Uncaught Error: Maximum call stack size of 8339456 bytes (zend.max_allowed_stack_size - zend.reserved_stack_size) reached. Infinite recursion? in /wp-content/plugins/product-configurator-for-woocommerce/inc/base/choice.php:29](http://boysmods.com/httpdocs/wp-content/plugins/product-configurator-for-woocommerce/inc/base/choice.php:29)

Which points to this file at line 29.

The Choice object is serialized and stored in the cart_item_meta.
What could be causing this to be unserialized again and again if Multi Currency is enabled?

Hoping someone will have an idea of where to look.
Marc

[frosso]

Hey @marcusig ! 👋

Thank you for the report! I accessed your test site, and added this product to the cart: https://demos.mklacroix.com/monpetitmagasin/product/configurable-product/?load_config_from_cart=688792b0ef64035871d317d92f77cfe5&open_configurator=1

Accessing the cart or checkout pages works fine on your test site.

I also checked https://www.boysmods.com/shop/ , but adding the product to the cart & accessing the cart worked fine.

Could you please confirm if the fatal error is reproducible on your test site, or if some plugin update mitigated the issue?
Or could you please assist me with some additional instructions on how to reproduce the error?

Thank you!

[marcusig]

Hi @frosso

Thanks for looking into this.
I've been trying to resolve this but I have mixed results.

However I found more information about the root of the issue (which I forgot to post yesterday):

I have now identified that the issue is linked to the SubscriptionCompatibility:

• The subscription compatibility runs even though no subscription plugin is active:
  This is the running check:
  if ( class_exists( 'WC_Subscriptions' ) || class_exists( 'WC_Payments_Subscriptions' ) ) {

From what I understand, class_exists( 'WC_Payments_Subscriptions' ) is always true, so the subscription tests always run

get_subscription_type_from_cart seems to run many times, and with a configurable product in the cart, get_subscription_type_from_cart is executed into an infinite loop.

The issue seem to happen specifically with the session checks: WC()->session->get( 'cart' )

I edited my code to try to prevent the infinite loop.
however it is not 100% successful. While it works on that test site, I am currently experiencing that same issue on a customer's website: adding this product to the cart https://staging4.banks-lyon.co.uk/product/babygiftbox/ (under "Start building...")
and going to the cart. I have updated the configurator plugin on this site with my latest changes, but the error persists.

This site does not have Multi currency enabled, but it has 2 currencies listed in the Multi currency settings.
Removing the extra currency stops the error from happening.

[frosso]

Thank you for the additional details @marcusig !

I have now identified that the issue is linked to the SubscriptionCompatibility:

To confirm - did you mean to reference the WooCommerceSubscriptions class within WooPayments?

This site does not have Multi currency enabled, but it has 2 currencies listed in the Multi currency settings.
Removing the extra currency stops the error from happening.

Ok, thank you - that's also helpful!

[marcusig]

To confirm - did you mean to reference the WooCommerceSubscriptions class within WooPayments?

Yes that's correct. Here:

https://github.com/Automattic/woocommerce-payments/blob/develop/includes/multi-currency/Compatibility/WooCommerceSubscriptions.php#L64

This specific section is where the problem happens:
It fetches the cart from the session a bunch of times per request (get_subscription_type_from_cart is called a dozen times on a simple product, reading directly from the session that many times).