go-delve/delve · error

could not load swiss table groups field: %v

Error message

could not load swiss table groups field: %v

What it means

Set on a map Variable while Delve loads the swiss map table's 'groups' pointer field. tab.toField(it.tableFieldGroups) looks up a struct field named 'groups' on the maps.Table type in the debuggee; failure means the field could not be resolved — either the DWARF type of the table doesn't have that field, or reading the field's address from target memory failed. Delve throws it because iteration cannot proceed without the groups array pointer.

Source

Thrown at pkg/proc/mapiter.go:624

	tab = tab.maybeDereference()

	r := &swissTable{}

	field, err2 := tab.toField(it.tableFieldIndex)
	if err2 != nil {
		it.v.Unreadable = fmt.Errorf("could not load swiss table index field: %v", err2)
		return
	}
	r.index, err = field.asInt()
	if err != nil {
		it.v.Unreadable = fmt.Errorf("could not load swiss table index: %v", err)
		return
	}

	groups, err2 := tab.toField(it.tableFieldGroups)
	if err2 != nil {
		it.v.Unreadable = fmt.Errorf("could not load swiss table groups field: %v", err2)
		return
	}
	r.groups, err2 = groups.toField(it.groupsFieldData)
	if err2 != nil {
		it.v.Unreadable = fmt.Errorf("could not load swiss table groups data: %v", err2)
		return
	}

	field, err2 = groups.toField(it.groupsFieldLengthMask)
	if err2 != nil {
		it.v.Unreadable = fmt.Errorf("could not load swiss table groups lengthMask field: %v", err2)
		return
	}
	groupsLengthMask, err := field.asUint()
	if err != nil {
		it.v.Unreadable = fmt.Errorf("could not load swiss table group lengthMask: %v", err)
		return
	}

View on GitHub (pinned to a23773e6c3)

Solutions

1. Rebuild the target with full debug info (default go build; avoid -w -s and -trimpath issues)
2. Upgrade Delve to match your Go version's maps.Table layout
3. Check that the DWARF type of the map is a real Go map, not a reinterpreted/aliased type
4. Fall back to inspecting the map via program output or a breakpoint on map-using code

Example fix

// before
go build -ldflags="-s -w" -o app .
// after: keep DWARF for debugging
go build -gcflags="-N -l" -o app .

if v != nil && v.Unreadable != nil { return v.Unreadable } // bail before using v.Value or children

func mapReadable(v *proc.Variable) (*proc.Variable, error) { if v == nil { return nil, errors.New("nil variable") }; if v.Unreadable != nil { return nil, v.Unreadable }; return v, nil }

// no panic is thrown; treat v.Unreadable as the error channel
if v.Unreadable != nil { log.Warnf("map not inspectable: %v", v.Unreadable); return defaultView }

When it happens

Trigger: Iterating any non-small swiss map when loadCurrentTable cannot resolve the 'groups' field of the maps.Table struct from the binary's DWARF info or from process memory.

Common situations: Binary compiled with -ldflags="-w -s" or trimmed DWARF; Go toolchain version where Table's field was renamed/restructured; debugging a core dump or minimized binary with incomplete type info.

Related errors

• could not load swiss table index: %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
• could not load swiss map group ctrl: %v

AI-assisted analysis of go-delve/delve@a23773e6c3 (2026-08-31). Data as JSON: /api/errors/7f75a7e40fdb8dc5. Report an issue: GitHub.