Consistent images/edit server_error

Since I started trying to use the image edits API this week, I have consistently got 500 code responses. This is the inpainting/outpainting API, which is only available for Dall-E 2.
Docs here:

Am I doing something wrong?

I haven’t got through to OpenAI support and can’t see anything online about any downtime…

The request I’m making:

-H "Authorization: Bearer $TOKEN" 
-F image="@image.png" 
-F mask="@mask.png" 
-F model="dall-e-2" 
-F prompt="A sunlit indoor lounge area with a pool containing a flamingo" 
-F n=1 
-F size="1024x1024"

The response I get:

"error": {
"code": null,
"message": "The server had an error processing your request. Sorry about that! You can retry your request, or contact us through our help center at if you keep seeing this error. (Please include the request ID ... in your email.)",
"param": null,
"type": "server_error"