We want to provide some guidance regarding the PayPal Smart Checkout integration with InstantPayPal.

Issue:
In some hosting environments, especially those with strict security headers like Cross-Origin-Opener-Policy: same-origin, the Smart Checkout popup may fail to open. When this happens, the PayPal SDK falls back to the in-context iframe, and a temporary blank window (about:blank) may appear.

Important Notes:

This behavior is caused by browser security policies and hosting server headers, not by the plugin or PayPal account configuration.

The blank popup window can be confusing, but it does not prevent the transaction from completing.

Recommended Workarounds:

Redirect Flow: Use the action=pay redirect flow in the plugin settings. This avoids the popup attempt and works reliably in all hosting environments.

Hosting Configuration: If possible, adjust your server headers to allow PayPal popups. For example, setting Cross-Origin-Opener-Policy: same-origin-allow-popups for the checkout page can help.

Testing:
You can always test your Smart Checkout setup using our demo site https://demo.storejextensions.org/instpp
to verify that everything works as expected without the blank window.