HTTP 500 Error creating Invoices

I’ve been using a custom written API integration to send invoices to Freeagent for years. It’s always worked fine.
This morning, the calls to Create Invoice stoped working. Only result I get in the HTTP header is this:

HTTP/1.1 500 Internal Server Error
Date: Thu, 13 Jun 2024 09:51:30 GMT
Content-Type: application/json
Transfer-Encoding: chunked
Connection: keep-alive
Server: nginx
Cache-Control: no-store
Pragma: no-cache
X-Request-Id: 1-666ac122-57834f4802207cb2448e1108
X-Rev: cefb506815ed0d726a04a4e228958b1f2e862dbc
X-Host: ip-10-132-213-28
X-Runtime: 0.206036
X-Frame-Options: SAMEORIGIN
X-XSS-Protection: 1; mode=block
Referrer-Policy: strict-origin-when-cross-origin
vary: Origin
Strict-Transport-Security: max-age=31536000
X-Content-Type-Options: nosniff

Payload JSON example is:

	"invoice" : 
		"bank_account" : "",
		"comments" : "",
		"contact" : "",
		"currency" : "GBP",
		"dated_on" : "2024-6-13",
		"ec_status" : "",
		"invoice_items" : 
				"description" : "13/06/2024\rline 1",
				"price" : "1",
				"quantity" : 1,
				"sales_tax_rate" : 20
		"payment_terms_in_days" : 28,
		"reference" : "GTECH2624"

Nothing has changed at my end - is this a Freeagent side issue?

Hi there :wave: James from FreeAgent here.

Thanks for getting in contact.

We noticed some issues earlier and have now deployed a fix. The timeframe of this incident was between 10:33 and 10:57.

We have a Status page for any further updates, this particular incident though has now been marked as resolved.

Please do let us know if you require any further help, we’ll be happy to take a look for you.

Best regards,