Image Optimization Troubleshooting

Learn how to troubleshoot Image Optimization errors related to image limits, formats, Content-Type values, transformation parameters, and cached variants.

Use the following checks when an Image Optimization request returns an error or does not produce the expected transformation.

Resolve 415 Unsupported Media Type errors

A 415 Unsupported Media Type response indicates that Image Optimization cannot process the requested image.

A 415 Unsupported Media Type response can occur when:

• The image exceeds the applicable file size or resolution limit.

• The source image format is not supported.

• The file extension and the Content-Type returned by the origin do not match.

Check file size and resolution

Image Optimization supports source images up to 100 MB.

A maximum resolution of 3000 × 3000 px applies to the following modules:

• mnresize

• mncrop

• mncropresize

• mnpadding

• mncustomcrop

Requests that exceed an applicable limit return 415 Unsupported Media Type.

To resolve the issue:

• Reduce the source image file size if it exceeds 100 MB.

• Reduce the image resolution when using a module subject to the 3000 × 3000 px limit.

• Replace the source image at the origin with a version that meets the applicable limits.

Check the source image format

Image Optimization supports the following source formats:

• JPG

• PNG

Requests using unsupported source formats return 415 Unsupported Media Type.

To resolve the issue:

• Convert the source image to JPG or PNG.

• Update the image URL to reference the supported source image.

Check Content-Type consistency

A 415 Unsupported Media Type response can occur when the image extension does not match the Content-Type returned by the origin.

For example:

Property	Value
File extension	.png
Origin Content-Type	image/x-ms-bmp

Although the URL uses a supported .png extension, the media type returned by the origin is not consistent with the expected image format.

Recommended resolution

Configure the origin or storage service to return the correct Content-Type for the source image.

For a PNG image:

Content-Type: image/png

Depending on the origin or storage service, correcting the Content-Type may require updating the object's metadata or uploading the image again.

Temporary workaround

If the origin configuration cannot be changed immediately, use a Page Rule to override the response header for the affected path.

For a PNG image:

• Match the affected .png path.

• Configure the response header as follows:

Content-Type: image/png

Overriding the Content-Type header does not change the actual file format. Use a header override only when the file content matches the configured media type.

Resolve transformation request errors

A transformation request can fail even when the source image meets the supported format and size requirements.

Check transformation parameters

Verify that the requested URL follows the syntax defined for the selected Image Optimization module.

Check that:

• The correct module name is used.

• Required parameters are present.

• Numeric parameters contain valid values.

• The parameters follow the required order.

• The requested modules do not use an unsupported combination.

See Image Optimization for module syntax, parameters, and limitations.

Resolve cache-related inconsistencies

Each transformed image URL creates a separate cache object. Previously cached content or headers can therefore remain associated with an individual transformed URL.

Clear a cached variant

After correcting the source image, origin headers, or transformation request:

1. Purge the affected transformed image URL.

2. Request the transformed URL again.

3. Verify the response and transformed image.

Purging the original image URL does not invalidate separately cached transformed variants. Purge each affected transformed URL individually.

When to contact Medianova Support

Contact Medianova Support if the source image meets the applicable format, file size, resolution, and Content-Type requirements but the issue continues after purging the affected transformed URL.

Include the following information:

• CDN Resource name

• Source image URL

• Transformed image URL

• Image Optimization module

• Observed HTTP status code

• Approximate time of the request