After generating a Resizer URL for an external image URL, there are cases where the Resizer URL continues to return a 5xx error. Since 5xx errors have a negative impact on SEO, we believe that a 4xx error should be returned instead.
For example, assume that the following Resizer URL was generated for the external image URL https://images.example.com/sample.jpg.
Resizer URL: https://www.example.com/resizer/v2/https%3A%2F%2Fimages.example.com%2Fsample.jpg?auth=dummy
The current behavior of the Resizer is as follows:
If https://images.example.com/sample.jpg returns a 403 error, the Resizer URL returns a 503 error.
If images.example.com becomes an invalid domain, the Resizer URL returns a 502 error.
As long as this situation continues, the number of 5xx image URL errors in Google Search Console will continue to increase indefinitely on our website.
Daiki Takahashi
Hi Daiki, thanks for submitting this idea.
Yes it makes sense to return 4xx rather than 5xx since 4xx are still considered expected response from a server while 5xx are usually unexpected states.