MiniMax-AI/skills · error · InvalidOperationException

Relationship {oldRelId} does not point to an ImagePart.

Error message

Relationship {oldRelId} does not point to an ImagePart.

What it means

`throw new InvalidOperationException($"Relationship {oldRelId} does not point to an ImagePart.")` in `ImageSamples.ReplaceExistingImage`. The method looks up a part by relationship id (`mainPart.GetPartById(oldRelId)`) and checks whether it is an `ImagePart`. If the rId points to a different part type (hyperlink, stylesheet, header, embedded object) the replace cannot proceed because `FeedData` would corrupt unrelated content.

Source

Thrown at skills/minimax-docx/scripts/dotnet/MiniMaxAIDocx.Core/Samples/ImageSamples.cs:500

    // ── 8. Replace Existing Image ──────────────────────────────────────

    /// <summary>
    /// Replaces an existing image by updating the ImagePart data behind a
    /// known relationship ID. The Blip.Embed attribute (rId) stays the same;
    /// only the binary content changes. This avoids needing to rebuild the
    /// entire Drawing XML tree.
    /// </summary>
    /// <param name="mainPart">The MainDocumentPart containing the image relationship.</param>
    /// <param name="oldRelId">The existing relationship ID (e.g., "rId5") of the image to replace.</param>
    /// <param name="newImagePath">Path to the replacement image file.</param>
    public static void ReplaceExistingImage(
        MainDocumentPart mainPart, string oldRelId, string newImagePath)
    {
        // Look up the existing ImagePart by its relationship ID
        OpenXmlPart part = mainPart.GetPartById(oldRelId);
        if (part is not ImagePart imagePart)
        {
            throw new InvalidOperationException(
                $"Relationship {oldRelId} does not point to an ImagePart.");
        }

        // Feed new image data into the existing part.
        // This replaces the binary content while keeping the same rId.
        using (FileStream stream = new FileStream(newImagePath, FileMode.Open))
        {
            imagePart.FeedData(stream);
        }

        // NOTE: If the new image has different dimensions, you should also
        // update the Extent.Cx/Cy and A.Extents.Cx/Cy in the Drawing element.
        // Find all Blip elements referencing this relId:
        //
        //   var blips = mainPart.Document.Descendants<A.Blip>()
        //       .Where(b => b.Embed == oldRelId);
        //   foreach (var blip in blips)
        //   {

View on GitHub (pinned to 60aaae52bb)

Solutions

Extract the rId from the image's `a:blip r:embed` (Drawing) element, not from hyperlinks or other relationships.
Before calling, verify with `mainPart.GetPartById(oldRelId) is ImagePart`.
Enumerate `mainPart.ImageParts` to find the correct rId for the image you intend to replace.

Example fix

// before — rId came from a hyperlink, not the image blip
ImageSamples.ReplaceExistingImage(mainPart, "rId3", newPath); // rId3 is a hyperlink

// after — use the blip's r:embed value
// <a:blip r:embed="rId5"/>
ImageSamples.ReplaceExistingImage(mainPart, "rId5", newPath);

Defensive patterns

Strategy: type-guard

Validate before calling

void ReplaceImage(MainDocumentPart mainPart, string oldRelId, string newPath)
{
    if (mainPart.GetPartById(oldRelId) is not ImagePart)
        throw new ArgumentException($"{oldRelId} is not an image relationship.", nameof(oldRelId));
    ImageSamples.ReplaceExistingImage(mainPart, oldRelId, newPath);
}

Type guard

bool IsImageRelationship(MainDocumentPart mainPart, string relId) =>
    mainPart.GetPartById(relId) is ImagePart;

Try / catch

try
{
    ImageSamples.ReplaceExistingImage(mainPart, oldRelId, newImagePath);
}
catch (InvalidOperationException ex) when (ex.Message.Contains("ImagePart"))
{
    // find the real image rId from the Drawing's a:blip r:embed
    var realRid = FindBlipEmbedId(mainPart);
    ImageSamples.ReplaceExistingImage(mainPart, realRid, newImagePath);
}

Prevention

Always read the rId from the image's `<a:blip r:embed="...">`, never from hyperlinks or other relationships.
Pre-check `mainPart.GetPartById(relId) is ImagePart` before calling.
Enumerate `mainPart.ImageParts` to discover valid image rIds.
Log the part type when the check fails so the wrong source element is obvious.

When it happens

Trigger: Passing an `oldRelId` that exists but references a non-image relationship — e.g. a hyperlink rId, a styles/header/footer relationship, or a media relationship that is not an `ImagePart`. Also passing a stale rId copied from the wrong element.

Common situations: Reading an rId off the wrong XML element (e.g. a `w:hyperlink r:id` instead of an `a:blip r:embed`), an rId from an older version of the document, or assuming every rId in `document.xml` is an image.

Related errors

AI-assisted analysis of MiniMax-AI/skills@60aaae52bb (2026-08-13). Data as JSON: /api/errors/360361f329802d8d. Report an issue: GitHub.