go-delve/delve · error

filter not supported on breakpoint

Error message

filter not supported on breakpoint

What it means

When the 'args' command is used inside an 'on <bp>' breakpoint context, it only records a load configuration on the breakpoint; per-variable name filtering (the -r regex option parsed by parseVarArguments) is not supported in that mode, so Delve returns this error when a non-empty filter is detected.

Source

Thrown at pkg/terminal/command.go:2353

	return t.printSortedStrings(t.client.ListTypes(args))
}

func parseVarArguments(args string, t *Term) (filter string, cfg api.LoadConfig) {
	if v := config.Split2PartsBySpace(args); len(v) >= 1 && v[0] == "-v" {
		if len(v) == 2 {
			return v[1], t.loadConfig()
		} else {
			return "", t.loadConfig()
		}
	}
	return args, ShortLoadConfig
}

func args(t *Term, ctx callContext, args string) error {
	filter, cfg := parseVarArguments(args, t)
	if ctx.Prefix == onPrefix {
		if filter != "" {
			return errors.New("filter not supported on breakpoint")
		}
		ctx.Breakpoint.LoadArgs = &cfg
		return nil
	}
	vars, err := t.client.ListFunctionArgs(ctx.Scope, cfg)
	if err != nil {
		return err
	}
	return t.printFilteredVariables("args", vars, filter, cfg)
}

func locals(t *Term, ctx callContext, args string) error {
	filter, cfg := parseVarArguments(args, t)
	if ctx.Prefix == onPrefix {
		if filter != "" {
			return errors.New("filter not supported on breakpoint")
		}
		ctx.Breakpoint.LoadLocals = &cfg

View on GitHub (pinned to a23773e6c3)

Solutions

1. Drop the filter flag: 'on <bp> args' optionally with other load-config flags.
2. Apply the regex filter when you run args normally at a stopped point instead.
3. Use 'on <bp> print <expr>' for per-expression output at breakpoint hits.

Example fix

// before
(dlv) on 1 args -r user.*
// after
(dlv) on 1 args

// before recording breakpoint commands in 'on' context
func validateOnArgsCmd(ctxPrefix, args string) error {
    if ctxPrefix == "on" && strings.Contains(args, "-r") {
        return errors.New("filter (-r) not allowed with 'on <bp> args'")
    }
    return nil
}

if err := cmd.Args(term, ctx, args); err != nil {
    if err.Error() == "filter not supported on breakpoint" {
        // retry without the filter flag
        return cmd.Args(term, ctx, stripFilterFlags(args))
    }
    return err
}

When it happens

Trigger: Running 'on <bp> args -r <pattern>' (any filter flag parsed by parseVarArguments yielding filter != "") with ctx.Prefix == onPrefix in args() (pkg/terminal/command.go).

Common situations: Users copying their usual 'args -r foo.*' invocation into an 'on' block without realizing filters only apply to live listing, not breakpoint-configured argument loading.

Related errors

• too many arguments to trace
• argument of deferred must be a number greater than 0 (use 's
• too many arguments to restart
• Invalid next count
• missing filename after -save flag

AI-assisted analysis of go-delve/delve@a23773e6c3 (2026-08-31). Data as JSON: /api/errors/894f7a0188ba3ae4. Report an issue: GitHub.