PayPal not working on a website: find the step

Most of these failures happen out of the owner's sight. The PayPal script loads from PayPal's own address, so an ad blocker, a privacy setting or a strict content security policy can stop it, and the button never renders. Mobile browsers and in-app browsers can block a popup that the page did not open straight from a tap, so the window never appears. A test payment from your own laptop often works, because your browser has no blocker and your account is already set up. The buyer who finds the button gone or the window blank has no way to tell you why.

• Open the console before you click. A blocked PayPal script shows up as a failed request in the network tab.
• Press the button on a phone with no ad blocker, then again in a private window, and compare the two.
• Check which client ID the live page loads. A sandbox ID on the live site fails for real buyers.
• Compare the item total, shipping and tax with the amount sent to PayPal. A mismatch is refused.
• Confirm your server records the order after the buyer approves, and logs any error it gets back.

A buyer reaches PayPal after the cart and the shipping form. The button is the first point: a script from PayPal's address draws it, and if that script is blocked, the spot stays empty. The second point is the window. PayPal opens in a popup or a new tab, and a popup the browser does not allow shows nothing at all. Inside a messaging app on an iPhone, the window may never open.

The third point is the amount. PayPal receives the total you send along with the line items, and it refuses a payment whose parts do not add up, or whose currency your account cannot take. The buyer sees an error inside the PayPal window and returns to your page. The fourth point is the return. The buyer approves, PayPal sends them back, and your site must capture the order on its own side. If that call fails, the buyer has approved a payment your site never recorded, and nobody sees it until the buyer writes in.

A button that never appears, with a failed request to PayPal's address in the network tab, points at blocking or at a script that stopped earlier on the page. A window that never opens, with a popup message in the console, points at the click handler or the browser. A window that opens and shows an amount or currency error points at the totals or the account settings. A buyer who approves and returns to an empty order page points at the capture call, which your server log will show.

Check the client ID too. A sandbox ID on a live page can open the window and then refuse the buyer, while your own sandbox tests keep passing. Compare the ID in the live page source with the account you think you are using. A sandbox test proves only that the sandbox works, and says nothing about the live account.

Set the start page to your cart or checkout address and give the visitor the task. The run presses the PayPal button, then reports what the window showed: no button, a window that never opened, or an error about the amount or currency. It records the failed PayPal request and any console error on the step where it happened, with a screenshot. A phone run and a laptop run can differ, so run both.

The run stops at the PayPal step. Visitors cannot log in to a PayPal account or pay with a real card, so the test never finishes a payment and never shows the return to your site. It does not read your PayPal settings, so it cannot tell you which currencies your account accepts. Check the return yourself with a sandbox buyer, and read your server log for the capture call.

Checkout flow testing

The button can disappear after a theme update, a new tag manager container or a change to the client ID. Rerun the same visitors after each fix to see whether the button shows, the window opens and the buyer reaches the return. Owners who gate a store behind a site password, or who test each preview deploy, catch the next break before a buyer does.