[Cloudflare image resizing] persistent Error 9412 /HTTP 415 (apparently no origin revalidation) Cloudflare #workers-help

[Cloudflare image resizing] persistent Error 9412 ...

hkhl.

01/04/2024, 12:41 PM

Hi, please direct me to a different channel if it fits better elsewhere. I am doing worker image resizing as described here: https://developers.cloudflare.com/images/image-resizing/resize-with-workers/. Works as designed in general, but when I bulk add images to the origin storage (public Azure Blob Storage), while some of the new images are already requested through the worker, we sometimes get images that are stuck in an error state. These requests then always return

HTTP 415 Unsupported Media type

and

Cf-resized: err=9412

long after the origin image upload is complete (~ 60 min.) The only way to fix this is to purge the complete cache in the dashboard manually. I did a lot of debugging, and I don't see why Cloudflare does not revalidate the origin. - There is no custom caching in the worker - The origin does not send cache-control headers. - Manually purging a single upstream URL as described here https://developers.cloudflare.com/images/image-resizing/troubleshooting/#caching-and-purging does not work. (So it is some kind of cache issue)

hkhl.

01/04/2024, 12:41 PM

I tried to reproduce the origin state changes during the upload and there is a timeslot (stage 2, ~10 sec) while the upload is in progress where error 9412 /HTTP 415 seems the correct response. As far as I can see, the stages are 1) HTTP 404 (

Content-Type: application/xml, No Etag, No Cache-Control, No Last-Modified-At

) 2) HTTP 200 (

Content-Lenght: 0, Content-Type: image/jpeg, ETag: .., Last-Modified-At: ..., No Cache-Control

) 3) HTTP 200 (

Content-Lenght: ... , Content-Type: image/jpeg, ETag: .., Last-Modified-At: ..., No Cache-Control

) Stage 3 definitely returns the correct Image (it is picked up after the complete cache purge) I can see that stage 2 should trigger Error 9412 /HTTP 415, but it sends no

Cache-Control

, a different

ETag

, and a

Last -Modified-At

that is before the stage 3

Last-Modified-At

. Any stage 3 revalidation requests from Cloudflare with

If-Modified-Since

If-None-Match

would return the full image (I double-checked with curl), but it seems that Cloudflare caches the upstream response of stage 2 forever. Is this the expected behaviour? It only happens when there are resizing requests during stage 2 (That's why it never happened before going to production)

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