PATCH https://api.paypal.com/v2/checkout/orders INVALID_REQUEST

I might have found a possible problem, but can't see what is causing it.

Emailing myself the json_encode() of the data, for one order the JSON is broken into two lines, with "! " at the end of the first line and a space at the start of the second line. The first line is 2040 characters long.

This makes the JSON invalid, causing the problem.

Is this a red-herring, caused by emailing the JSON? I don't think so, but could be.

If this is a real symptom, what is inserting "! \n " into the JSON text?

Unfortunately, without reproducible steps, not actually sure how to help here.

My best guess is that the problem occurs when the JSON body is more than 2,040 characters, so for an order with a LOT of line items. I'll do some more testing when I get a spare moment, using an order with a huge JSON description.

Most odd. I now catch the Guzzle exception, and log the details. This allows the PayPal orders that fail in the PATCH to continue anyway.

GuzzleHttp\Exception\ClientException

Client error: `PATCH https://api.paypal.com/v2/checkout/orders/xxxxxxxxxxxxxxxxxxxxx` resulted in a `400 Bad Request` response:
{"name":"INVALID_REQUEST","message":"Request is not well-formed, syntactically incorrect, or violates schema.","debug_id (truncated...)

{"0":{"op":"replace","path":"\/purchase_units\/@reference_id=='default'","value":{"reference_id":"default","custom_id":"1234","invoice_id":"1234-1234567890","amount":{"currency_code":"GBP","value":"7.5","breakdown":{"item_total":{"currency_code":"GBP","value":"7.5"}}},"items":[{"name":"1296px \u00d7 864px JPEG download","unit_amount":{"currency_code":"GBP","value":"1.25"},"quantity":1,"sku":"DD1296x864"},{"name":"1296px \u00d7 864px JPEG download","unit_amount":{"currency_code":"GBP","value":"1.25"},"quantity":1,"sku":"DD1296x864"},{"name":"1296px \u00d7 864px JPEG download","unit_amount":{"currency_code":"GBP","value":"1.25"},"quantity":1,"sku":"DD1296x864"},{"name":"1296px \u00d7 864px JPEG download","unit_amount":{"currency_code":"GBP","value":"1.25"},"quantity":1,"sku":"DD1296x864"},{"name":"1296px \u00d7 864px JPEG download","unit_amount":{"currency_code":"GBP","value":"1.25"},"quantity":1,"sku":"DD1296x864"},{"name":"1296px \u00d7 864px JPEG download","unit_amount":{"currency_code":"GBP","value":"1.25"},"quantity":1,"sku":"DD1296x864"}]}},"purchase_units":[{"items":[{"name":"AGc19877, 1296px \u00d7 864px JPEG download"},{"name":"AG19650, 1296px \u00d7 864px JPEG download"},{"name":"AB00516, 1296px \u00d7 864px JPEG download"},{"name":"AG06613, 1296px \u00d7 864px JPEG download"},{"name":"AG06615, 1296px \u00d7 864px JPEG download"},{"name":"AG01394, 1296px \u00d7 864px JPEG download"}]}]}

(some possibly-sensitive data replaced with equivalent random text)

This was a shorter order, so nothing to do with the length of the JSON.

According to PhpStorm the JSON is valid.

Found the problem!

It was my own custom code, that modified the order line item titles sent to PayPal using PayPalEvents::CHECKOUT_CREATE_ORDER_REQUEST and PayPalEvents::CHECKOUT_UPDATE_ORDER_REQUEST.

For the first event, CREATE, the line item titles are stored in $params['purchase_units'][0]['items'].

For the second event, UPDATE, the line item titles are stored in $params[0]['value']['items'].

The code is working as designed.

Be careful if you want to modify order data using PayPalEvents::CHECKOUT_CREATE_ORDER_REQUEST => 'addCatnums' and PayPalEvents::CHECKOUT_UPDATE_ORDER_REQUEST, the data is in different places in each.