iOfficeAI/OfficeCLI · error · ArgumentException

drawing-group anchor XML is not a valid xdr:twoCellAnchor: {

Error message

drawing-group anchor XML is not a valid xdr:twoCellAnchor: {ex.Message}

What it means

The 'anchor-xml' string was passed to the OpenXML SDK constructor `new XDR.TwoCellAnchor(anchorXml)` and it threw. This means the value is present but is not parseable as an xdr:twoCellAnchor element — malformed XML, wrong root element, undeclared namespace prefix, or a non-XML payload (e.g. still base64-encoded). The original exception message is embedded for diagnosis.

Source

Thrown at src/officecli/Handlers/Excel/ExcelHandler.Add.cs:1135

                // to semantic leaf shapes when a group references package
                // parts such as images/charts.
                var groupSheetName = parentPartPath.TrimStart('/');
                var groupWorksheet = FindWorksheet(groupSheetName)
                    ?? throw new ArgumentException(
                        $"Sheet not found: {groupSheetName}. drawing-group must be added under a sheet.");
                properties ??= new Dictionary<string, string>();
                var anchorXml = properties.GetValueOrDefault("anchor-xml")
                    ?? throw new ArgumentException(
                        "'anchor-xml' property is required for drawing-group (verbatim xdr anchor XML)");

                XDR.TwoCellAnchor groupAnchor;
                try
                {
                    groupAnchor = new XDR.TwoCellAnchor(anchorXml);
                }
                catch (Exception ex)
                {
                    throw new ArgumentException(
                        $"drawing-group anchor XML is not a valid xdr:twoCellAnchor: {ex.Message}", ex);
                }
                if (groupAnchor.GetFirstChild<XDR.GroupShape>() == null)
                    throw new ArgumentException(
                        "drawing-group anchor XML must contain a top-level xdr:grpSp.");

                List<DumpDrawingHyperlinkSpec> groupHyperlinks;
                try
                {
                    groupHyperlinks = DecodeDumpDrawingHyperlinks(
                        properties.GetValueOrDefault("hyperlinks") ?? "");
                }
                catch (FormatException ex)
                {
                    throw new ArgumentException(
                        $"drawing-group 'hyperlinks' carrier is invalid: {ex.Message}", ex);
                }

View on GitHub (pinned to 1ced45e900)

Solutions

Ensure anchor-xml is raw, well-formed XML with the xdr namespace declared.
If you sourced it from a base64 field, decode it first (Convert.FromBase64String then UTF-8 decode).
Load it through XDocument.Parse in a scratch test to isolate the parse error from the SDK.
Confirm the root is <xdr:twoCellAnchor>, not a wrapper.

Example fix

// before — still base64 encoded
props["anchor-xml"] = "PHhkcjp0d29DZWxsQW5jaG9y...";
// after — decoded raw XML
props["anchor-xml"] = System.Text.Encoding.UTF8.GetString(
    Convert.FromBase64String("PHhkcjp0d29DZWxsQW5jaG9y..."));

Defensive patterns

Strategy: try-catch

Validate before calling

try { _ = System.Xml.Linq.XDocument.Parse(props["anchor-xml"]); }
catch (System.Xml.XmlException ex) { /* surface parse error before AddPart */ }

Type guard

static bool AnchorParses(string xml)
{ try { return System.Xml.Linq.XDocument.Parse(xml) != null; } catch { return false; } }

Try / catch

try { handler.AddPart(parent, "drawing-group", props); }
catch (ArgumentException ex) when (ex.Message.Contains("not a valid xdr:twoCellAnchor"))
{ /* inspect ex.InnerException, fix markup, decode if still base64 */ }

Prevention

Pre-parse anchor-xml with XDocument.Parse to catch XML errors early.
Decode base64 payloads before assigning to anchor-xml.
Confirm the root element is xdr:twoCellAnchor with the xdr namespace declared.

When it happens

Trigger: anchor-xml is truncated, has HTML-escaped entities (< instead of <), is missing the xdr namespace declaration, has a different root element (e.g. <xdr:wsDr> or <xdr:absoluteAnchor>), or was left base64-encoded from the dump.

Common situations: Copy-paste truncation of a large group anchor; a transport layer that HTML-escaped the XML; forgetting that the dump emits base64 XML elsewhere and assuming anchor-xml is also encoded; mismatched OpenXML SDK version that rejects the namespace.

Related errors

AI-assisted analysis of iOfficeAI/OfficeCLI@1ced45e900 (2026-08-13). Data as JSON: /api/errors/a13b6f423eee3b29. Report an issue: GitHub.