gohugoio/hugo · critical

Insert: unknown type %T

Error message

Insert: unknown type %T

What it means

An internal panic in contentNodeShifter.Insert (hugolib/content_map_page_contentnodeshifter.go:150). Insert handles old nodes of type contentNodeSingle, contentNodes, and contentNodesMap; any other concrete type for 'old' reaches the default panic branch.

Source

Thrown at hugolib/content_map_page_contentnodeshifter.go:150

		switch new := new.(type) {
		case contentNodeForSite:
			oldp := vv[new.siteVector()]
			updated := oldp != new
			if updated {
				resource.MarkStale(oldp)
			}
			vv[new.siteVector()] = new
			return vv, oldp, updated
		default:
			s := make(contentNodes, 0, len(vv)+1)
			for _, v := range vv {
				s = append(s, v)
			}
			s = append(s, new)
			return s, vv, false
		}
	default:
		panic(fmt.Sprintf("Insert: unknown type %T", old))
	}
}

func (s *contentNodeShifter) Shift(n contentNode, siteVector sitesmatrix.Vector, fallback bool) (contentNode, bool) {
	var exact contentNode
	switch v := n.(type) {
	case contentNodeLookupContentNode:
		exact = v.lookupContentNode(siteVector)
	default:
		panic(fmt.Sprintf("Shift: unknown type %T for %q", n, n.Path()))
	}

	if exact != nil {
		if !fallback {
			return exact, true
		}
		// If the exact match is backed by a file, return it directly.
		if wp, ok := exact.(contentNodeContentWeightProvider); ok && wp.contentWeight() > 0 {

View on GitHub (pinned to 52c9bd7908)

Solutions

1. Report a Hugo bug
2. Ensure inserted nodes conform to the recognized 'old' types
3. Upgrade Hugo

// Internal: ensure 'old' is a recognized type before Insert.
switch old.(type) {
case contentNodeSingle, contentNodes, contentNodesMap:
default:
    return errors.New("unrecognized old node type for Insert")
}

func isInsertableOld(old contentNode) bool {
    switch old.(type) {
    case contentNodeSingle, contentNodes, contentNodesMap:
        return true
    }
    return false
}

When it happens

Trigger: Insert is called with an 'old' node whose type is not contentNodeSingle, contentNodes, or contentNodesMap — an internal contract violation.

Common situations: Hugo internal bug; a custom node type introduced without updating the shifter.

Related errors

• DeleteFunc: unknown type %T
• Shift: unknown type %T for %q
• contentNodeToContentNodesPage: unexpected type %T
• no vectors
• no site found for matrix %s

AI-assisted analysis of gohugoio/hugo@52c9bd7908 (2026-08-09). Data as JSON: /api/errors/5d34b17c89940100. Report an issue: GitHub.