go-delve/delve · error

could not load swiss map group keys: %v

Error message

could not load swiss map group keys: %v

What it means

Set on a map Variable by loadCurrentGroup for swiss maps using the split-group (SwissMapGroupKindSplit) representation: the 'keys' array field of the group could not be resolved from DWARF. Delve throws it because it cannot access key storage without the keys field when the map stores keys and elems in separate arrays.

Source

Thrown at pkg/proc/mapiter.go:683

	g := &swissGroup{}

	var err2 error
	ctrl, err2 := group.toField(it.groupFieldCtrl)
	if err2 != nil {
		it.v.Unreadable = fmt.Errorf("could not load swiss map group ctrl: %v", err2)
		return
	}
	g.ctrls = make([]byte, ctrl.DwarfType.Size())
	_, err = ctrl.mem.ReadMemory(g.ctrls, ctrl.Addr)
	if err != nil {
		it.v.Unreadable = err
		return
	}

	if it.mapsplitgroup {
		g.keys, err2 = group.toField(it.groupFieldKeys)
		if err2 != nil {
			it.v.Unreadable = fmt.Errorf("could not load swiss map group keys: %v", err2)
			return
		}
		g.elems, err2 = group.toField(it.groupFieldElems)
		if err2 != nil {
			it.v.Unreadable = fmt.Errorf("could not load swiss map group elems: %v", err2)
			return
		}
	} else {
		g.slots, err2 = group.toField(it.groupFieldSlots)
		if err2 != nil {
			it.v.Unreadable = fmt.Errorf("could not load swiss map group slots: %v", err2)
			return
		}
	}

	it.group = g
}

View on GitHub (pinned to a23773e6c3)

Solutions

1. Upgrade Delve to the latest version matching your Go release
2. Rebuild the binary with full debug info (no -w -s)
3. Pin the Go toolchain to a Delve-supported version
4. Inspect map contents via program-side printing as a fallback

if v.Unreadable != nil { return } // split-group keys field unresolvable; rebuild target or upgrade Delve

func readable(v *proc.Variable) bool { return v != nil && v.Unreadable == nil }

if v.Unreadable != nil { return partialResult, v.Unreadable }

When it happens

Trigger: Iterating a large swiss map where groups are split (key/elem arrays separated for cache efficiency) and group.toField(it.groupFieldKeys) fails because the DWARF group type lacks a matching 'keys' field.

Common situations: Go version where split-group layout differs from Delve's expectation; binaries built with newer Go than the installed Delve supports; DWARF stripped or damaged by build/post-link flags.

Related errors

• could not load swiss table index: %v
• could not load swiss table groups field: %v
• could not load swiss table groups data: %v
• could not load swiss table groups lengthMask field: %v
• could not load swiss table group lengthMask: %v

AI-assisted analysis of go-delve/delve@a23773e6c3 (2026-08-31). Data as JSON: /api/errors/df7049b4dfdd8a66. Report an issue: GitHub.