go-delve/delve · error

could not load swiss map group elems: %v

Error message

could not load swiss map group elems: %v

What it means

Set on a map Variable by loadCurrentGroup when, in the split-group representation, the 'elems' array field of the group cannot be resolved from DWARF. Delve throws it because, alongside keys, the elems field is required to retrieve map values in split-group swiss maps.

Source

Thrown at pkg/proc/mapiter.go:688

		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
}

func (it *mapIteratorSwiss) key() *Variable {
	return it.curKey
}

func (it *mapIteratorSwiss) value() *Variable {

View on GitHub (pinned to a23773e6c3)

Solutions

1. Update Delve to a version supporting your Go toolchain's swiss map layout
2. Rebuild with default debug flags and a supported Go version
3. Verify debug info presence (go tool nm / readelf --debug-dump) on the binary
4. Fall back to application-level logging of the map

if v.Unreadable != nil { return } // split-group elems field unresolvable

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

if err := v.Unreadable; err != nil { log.Warnf("cannot read map values: %v", err); return }

When it happens

Trigger: Iterating a split-group swiss map where group.toField(it.groupFieldElems) fails: the group DWARF type lacks 'elems' or the field's type can't be read, typically from a Go runtime/Delve layout mismatch.

Common situations: Target built with a Go version whose internal/runtime/maps group struct differs; debugging with an outdated Delve; minimized or stripped binaries losing field metadata.

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/511cdcc4619cfc17. Report an issue: GitHub.