go-delve/delve · error

could not find target %d

Error message

could not find target %d

What it means

'target switch <pid>' searches the current target group for a live target with the given PID. If no valid target matches, Delve returns 'could not find target %d'. The PID must belong to a currently debugged (followed or attached) process that is still valid.

Source

Thrown at service/dap/command.go:322

			return "", fmt.Errorf("unknown argument %q to 'target follow-exec'", argv[0])
		}
	case "switch": // TODO: This may cause inconsistency between debugger and frontend.
		tgrp, unlock := s.debugger.LockTargetGroup()
		defer unlock()
		pid, err := strconv.Atoi(argv[1])
		if err != nil {
			return "", err
		}
		found := false
		for _, tgt := range tgrp.Targets() {
			if _, err = tgt.Valid(); err == nil && tgt.Pid() == pid {
				found = true
				tgrp.Selected = tgt
				tgt.SwitchThread(pid)
			}
		}
		if !found {
			return "", fmt.Errorf("could not find target %d", pid)
		}
		return fmt.Sprintf("Switched to process %d", pid), err
	default:
		return "", fmt.Errorf("unknown target command")
	}
}

View on GitHub (pinned to a23773e6c3)

Solutions

1. Run 'target list' to see valid target PIDs and pick one from that output.
2. Verify the child process is still alive; if it exited, re-launch or re-enable follow-exec before the exec occurs.
3. Check you are not confusing the dlv process PID or a shell PID with the debuggee PID.
4. If the target should exist but does not, check follow-exec is enabled with a regex matching the child's cmdline.

Example fix

// before (guessed pid)
target switch 99999
// after (use pid from target list)
target list
target switch 4242

// query valid targets first via the evaluate command:
out := runEval("target list")
validPids := parsePidsFromList(out) // column 2 of each line
if !validPids[pid] {
    return fmt.Errorf("pid %d not debugged; pick from target list", pid)
}

When it happens

Trigger: Running 'target switch 1234' where 1234 was never debugged, has exited (tgt.Valid() != nil), or belongs to an unrelated process on the system.

Common situations: Trying to switch to a child process that already exited during follow-exec debugging; using the parent shell PID instead of the debuggee PID; stale PID from a previous session; switching while only one target exists and mistyping the PID.

Related errors

• count/len must be a positive integer
• expected argument after -size
• size must be a positive integer (<=8)
• no address specified
• command not available

AI-assisted analysis of go-delve/delve@a23773e6c3 (2026-08-31). Data as JSON: /api/errors/d643e1aa1d6c14e2. Report an issue: GitHub.