Why is the Format parameter inside my upload preset being ignored?

When both Allowed-formats and Format parameters are specified in an upload preset, their behavior differs from when they are used separately.

Default Behavior

• If Allowed-formatsis set, only those formats are whitelised for upload (e.g., if jpg is set for this field, only jpg files can be uploaded ). Otherwise, any format can be used.
• If Format is set (e.g., jpg), all uploaded files—regardless of their original format—will be automatically converted to the specified format upon upload (i.e.,jpg here).

Modified Behavior

When both Allowed-formats and Format are defined, their functionality changes:

• Allowed-formats acts as a whitelist, allowing only the specified formats to be uploaded. Any format not included will be rejected.
• Format applies only to files not included in the Allowed-formats list. These files will be converted to the format specified in the Format parameter.
• Files with formats included in the Allowed-formats list will be uploaded as-is, preserving their original format.

Summary

• Allowed-formats restricts which file types can be uploaded.
• Format(when combined with Allowed-formats) only converts files that don’t match the allowed formats. Allowed file types remain unchanged.