halo-dev/halo · error · ServerWebInputException

Required url is missing.

Error message

Required url is missing.

What it means

Thrown as a ServerWebInputException (HTTP 400) from the UploadFromUrlRequest compact constructor (user-center attachment endpoint) when the 'url' field is null. The record's URL field is declared required; the compact constructor enforces non-null because Spring may bind an absent body to a null url rather than rejecting binding.

Source

Thrown at application/src/main/java/run/halo/app/core/endpoint/uc/AttachmentUcEndpoint.java:315

    @Override
    public GroupVersion groupVersion() {
        return GroupVersion.parseAPIVersion("uc.api.storage.halo.run/v1alpha1");
    }

    /**
     * User-center request payload for uploading from a URL.
     *
     * @param url remote file URL to transfer into user-center storage
     * @param filename custom file name
     */
    @Schema(name = "UcUploadFromUrlRequest")
    public record UploadFromUrlRequest(
            @Schema(requiredMode = REQUIRED) URL url, String filename) {

        public UploadFromUrlRequest {
            if (Objects.isNull(url)) {
                throw new ServerWebInputException("Required url is missing.");
            }
        }
    }

    /**
     * Multipart payload for uploading a post attachment.
     *
     * @param file attachment data
     * @param postName post {@code metadata.name}
     * @param singlePageName single page {@code metadata.name}
     */
    @Schema(types = "object")
    public record PostAttachmentRequest(
            @Schema(requiredMode = REQUIRED) FilePart file,

            @Schema(requiredMode = NOT_REQUIRED) String postName,

            @Schema(requiredMode = NOT_REQUIRED) String singlePageName) {

View on GitHub (pinned to d2f5165f9c)

Solutions

1. Provide a non-null 'url' field in the request body, e.g. {"url":"https://example.com/img.png","filename":"img.png"}.
2. Add client-side required-field validation on the URL input before submit.
3. Ensure the URL parses as java.net.URL (scheme + host present).

Example fix

// before:  {}
// after:   { "url": "https://example.com/photo.png", "filename": "photo.png" }

// require a non-null, parseable URL before upload-from-URL
if (url == null || url.isBlank()) {
    showUserError("URL is required");
    return;
}
try { new java.net.URL(url); } catch (Exception e) {
    showUserError("Enter a valid URL"); return;
}

When it happens

Trigger: POST to the user-center upload-from-URL endpoint (AttachmentUcEndpoint) with a JSON body that omits 'url', sends url:null, or sends an empty body. The record constructor runs and Objects.isNull(url) is true.

Common situations: Frontend submitted the form before entering a URL; client serialized the field with the wrong key; paste left the field empty; API test posted {} intentionally.

Related errors

• Required url is missing.
• Policy name must not be blank
• Invalid part of policyName
• Invalid type of parameter 'file'.
• urls must not be empty.

AI-assisted analysis of halo-dev/halo@d2f5165f9c (2026-08-14). Data as JSON: /api/errors/dbd04aafec095c7e. Report an issue: GitHub.