wavetermdev/waveterm · error

error formatting metadata: %v

Error message

error formatting metadata: %v

What it means

When --print is passed, setbg serializes the computed metadata map to indented JSON with json.MarshalIndent and prints it instead of applying it. json.MarshalIndent only fails if the map contains a value JSON cannot encode (channels, funcs, complex numbers, or cyclic structures). With the current meta values this is practically unreachable, so the error indicates an internal/logic bug rather than user input.

Source

Thrown at cmd/wsh/cmd/wshcmd-setbg.go:202

			default:
				bgStyle += " center/cover no-repeat"
			}
		}

		meta["bg"] = bgStyle
	}

	if borderColorChanged {
		meta["bg:bordercolor"] = setBgBorderColor
	}
	if activeBorderColorChanged {
		meta["bg:activebordercolor"] = setBgActiveBorderColor
	}

	if setBgPrint {
		jsonBytes, err := json.MarshalIndent(meta, "", "  ")
		if err != nil {
			return fmt.Errorf("error formatting metadata: %v", err)
		}
		WriteStdout("%s\n", string(jsonBytes))
		return nil
	}

	// Resolve tab reference
	id := blockArg
	if id == "" {
		id = "tab"
	}
	oRef, err := resolveSimpleId(id)
	if err != nil {
		return err
	}

	// Send RPC request
	setMetaWshCmd := wshrpc.CommandSetMetaData{
		ORef: *oRef,

View on GitHub (pinned to a4447c1563)

Solutions

1. Re-run with --print to reproduce; if it fires on stock waveterm, report a bug to the Wave Terminal repository
2. Check any local modifications to wshcmd-setbg.go for values placed into meta that are not JSON-marshalable (funcs, channels)
3. Work around by omitting --print and applying the change directly

try {
  const out = execSync(`wsh setbg ${args} --print`, { stdio: "pipe" });
  console.log(out.toString());
} catch (e) {
  if (String(e.stderr).includes("error formatting metadata")) {
    console.error("Internal marshal failure — report a waveterm bug");
  } else throw e;
}

When it happens

Trigger: Practically only when the metadata map ends up containing a non-JSON-encodable value — a code-level bug (e.g. a bad type stored into meta), not a user-input error. Normal user invocations of `wsh setbg --print ...` never hit this.

Common situations: Custom builds or patches to setbg that inject unsupported types into meta; otherwise essentially never encountered by end users.

Understand the failure class

Background: json.Marshal / "failed to marshal" errors in Go: why "unsupported type" happens and how to fix it — this error's family across 22 libraries.

Related errors

• failed to marshal JSON: %v
• formatting version info: %v
• json encoding: %w
• no files or message provided
• too many files (maximum %d files allowed)

AI-assisted analysis of wavetermdev/waveterm@a4447c1563 (2026-09-01). Data as JSON: /api/errors/812ea467c23521c2. Report an issue: GitHub.