Hi All, I solved now this issue. Paypal requirements is PHP 5.3 and mine is PHP 5.2 due to PCI upgrades. https://www.paypal.com/us/smarthelp/article/what-version-of-php-is-required-to-use-the-paypal-sdk-for-php-ts1057 I contacted my host to upgrade my PHP version to 5.3 but they can only offer 5.5 to latest ones. In my thinking it is best to used 5.3 because the PHP codes that I have written supports only to PHP 5.2 and to avoid errors problem. After upgrading to PHP 5.5, Paypal Express Checkout works. But expect errors on screen to display and you should fix those deprecated errors. Thanks
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