WooCommerce PayPal Payments Plugin Error After Update

  • premkumarbsetxt

    (@premkumarbsetxt)


    2 weeks, 2 days ago

    We recently updated the WooCommerce PayPal Payments plugin from v3.3.0 to v4.0.4 on our live environment.

    Environment details:

    • WordPress version: 6.9.1
    • WooCommerce version: 10.7.0
    • WooCommerce PayPal Payments: v3.3.0 → v4.0.4

    After the update, the payment flow appears to work correctly, but continuous error logs are being generated repeatedly:

    2026-05-26T09:08:13+00:00 Error – Cart simulation failed: Error adding products to cart.
    2026-05-26T09:08:17+00:00 Error – Cart simulation failed: Error adding products to cart.
    2026-05-26T09:09:09+00:00 Error – Cart simulation failed: Error adding products to cart.

    We have already performed the following troubleshooting steps:

    • Cleared transients
    • Cleared WooCommerce customer sessions
    • Verified no cache plugin is installed
    • Tested basic checkout flow
    • Issue not reproducible in the dev environment

    Could you please help us identify the root cause of these continuous “Cart simulation failed” logs after the plugin update?

    Thanks.

Viewing 3 replies - 1 through 3 (of 3 total)
  • Plugin Support Krystian Syde

    (@inpsydekrystian)

    2 weeks, 2 days ago

    Hello @premkumarbsetxt

    You can apply the following workaround, which should resolve the error:

    add_filter( 'woocommerce_paypal_payments_simulate_cart_enabled', '__return_false' );

    This disables the cart simulation feature, which is mainly used for compatibility with certain third-party features and Pay Later calculations. It is safe to disable and should prevent this.

    Please let me know if this resolves the issue on your end.

    Kind Regards,
    Krystian

    Thread Starter premkumarbsetxt

    (@premkumarbsetxt)

    2 weeks, 2 days ago

    Hi @inpsydekrystian ,

    Thank you for the workaround suggestion.

    We applied the following filter:

    add_filter( ‘woocommerce_paypal_payments_simulate_cart_enabled’, ‘__return_false’ );

    However, after applying it, we are still seeing continuous error logs

    2026-05-26T10:09:09+00:00 Error #4819 – Cart simulation failed: Could not validate nonce.
    2026-05-26T10:09:09+00:00 Error #9493 – Cart simulation failed: Could not validate nonce.

    Additional details:

    • No cache plugin is installed
    • Cleared WooCommerce transients and customer sessions

    Could you please advise on the next steps or whether there are any additional settings/hooks that need to be adjusted after disabling cart simulation?

    Thanks.

    Plugin Support Krystian Syde

    (@inpsydekrystian)

    2 weeks, 1 day ago

    Hello @premkumarbsetxt

    If Google Pay or Apple Pay is enabled on the site, then these cart simulation logs can generally be ignored. Even when the simulation filter is disabled, the plugin may still perform limited cart simulation-related requests internally for Apple Pay / Google Pay flows, as those express payment methods rely on cart validation and recalculation mechanisms during initialization.

    There is likely nothing additional that needs adjustment at this stage unless you are also experiencing actual checkout/payment issues alongside the logs.

    Kind Regards
    Krystian

Viewing 3 replies - 1 through 3 (of 3 total)

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