cilium/cilium · error

could not transcode %q value: %w

Error message

could not transcode %q value: %w

What it means

Before writing, the kvstore 'set' command runs tryTranscodeFromJSON on the trimmed file content; if transcoding fails (e.g. the key has a registered schema/type and the file content is not valid or compatible JSON) it wraps the error as 'could not transcode %q value: %w'.

Source

Thrown at pkg/kvstore/commands.go:57

			Args:    "key value-file",
		},
		func(s *script.State, args ...string) (script.WaitFunc, error) {
			if len(args) != 2 {
				return nil, fmt.Errorf("%w: expected key and value file", script.ErrUsage)
			}
			key := args[0]
			value, err := os.ReadFile(s.Path(args[1]))
			if err != nil {
				return nil, fmt.Errorf("could not read %q: %w", s.Path(args[1]), err)
			}

			// As this is a dev/test only command, we can be a bit more
			// aggressive with trimming whitespace to simplify our test scripts.
			value = bytes.TrimSpace(value)

			value, err = tryTranscodeFromJSON(key, value)
			if err != nil {
				return nil, fmt.Errorf("could not transcode %q value: %w", key, err)
			}

			return nil, c.client.Update(s.Context(), key, value, false)
		},
	)
}

func (c cmds) delete() script.Cmd {
	return script.Command(
		script.CmdUsage{
			Summary: "delete kvstore key-value",
			Args:    "key",
		},
		func(s *script.State, args ...string) (script.WaitFunc, error) {
			if len(args) != 1 {
				return nil, fmt.Errorf("%w: expected key", script.ErrUsage)
			}
			return nil, c.client.Delete(s.Context(), args[0])

View on GitHub (pinned to ac7b90affa)

Solutions

1. Validate the value file contains well-formed JSON (jq . value.txt)
2. Trim stray whitespace/newlines (the command already trims spaces but content must still be valid JSON)
3. Check whether the key has a registered transcoding and what type it expects

Example fix

// before
// value.txt: {"a": 1,}
// after
// value.txt: {"a": 1}

if _, err := json.Valid(value); !err {
    return fmt.Errorf("value for %q is not valid JSON", key)
}

When it happens

Trigger: tryTranscodeFromJSON(key, value) returns an error — the value file content is not valid JSON when the key requires JSON decoding, or doesn't match the expected shape for that key.

Common situations: Malformed JSON in the value file (trailing commas, unquoted strings); whitespace/newlines breaking parsing for keys expecting strict JSON; writing a JSON value to a key registered for a different type.

Understand the failure class

Background: JSON parse error: "Unexpected token" / "not valid JSON" / "failed to parse" — what JSON parsers are really complaining about — this error's family across 45 libraries.

Related errors

• %w: expected key and value file
• could not read %q: %w
• %w: expected key
• error listing %q: %w
• remote cluster configuration required but not found

AI-assisted analysis of cilium/cilium@ac7b90affa (2026-08-31). Data as JSON: /api/errors/9a5c3611d4030bae. Report an issue: GitHub.