apache/pulsar · error · IllegalArgumentException

'${DEFAULT_CONFIG}' can't be modified.

Error message

'${DEFAULT_CONFIG}' can't be modified.

What it means

FileConfigStore (the pulsar-shell local config store) reserves the name DEFAULT_CONFIG for built-in defaults. putConfig rejects any ConfigEntry with that name, throwing IllegalArgumentException, so the reserved profile cannot be overwritten; create/use a named profile instead.

Source

Thrown at pulsar-client-tools/src/main/java/org/apache/pulsar/shell/config/FileConfigStore.java:88

        try (final BufferedInputStream buffered = new BufferedInputStream(new FileInputStream(file));) {
            try {
                fileConfig = mapper.readValue(buffered, FileConfig.class);
            } catch (MismatchedInputException mismatchedInputException) {
                fileConfig = new FileConfig();
            }
        }
    }

    private void write() throws IOException {
        try (final BufferedOutputStream bufferedOutputStream = new BufferedOutputStream(new FileOutputStream(file));) {
            mapper.writeValue(bufferedOutputStream, fileConfig);
        }
    }

    @Override
    public void putConfig(ConfigEntry entry) throws IOException {
        if (DEFAULT_CONFIG.equals(entry.getName())) {
            throw new IllegalArgumentException("'" + DEFAULT_CONFIG + "' can't be modified.");
        }
        ConfigStore.cleanupValue(entry);
        fileConfig.configs.put(entry.getName(), entry);
        write();
    }

    @Override
    public ConfigEntry getConfig(String name) {
        if (DEFAULT_CONFIG.equals(name)) {
            return defaultConfig;
        }
        return fileConfig.configs.get(name);
    }

    @Override
    public void deleteConfig(String name) throws IOException{
        if (DEFAULT_CONFIG.equals(name)) {
            throw new IllegalArgumentException("'" + DEFAULT_CONFIG + "' can't be deleted.");

View on GitHub (pinned to 820761864e)

Solutions

1. Save settings under a named profile, e.g. putConfig with name 'myprofile', then reference that profile at startup.
2. Do not attempt to modify the default profile; copy its values into a new named entry and change that.
3. Adjust scripts that iterate configs to skip the reserved default entry when writing back.

Example fix

// before
store.putConfig(new ConfigEntry("default", "http://localhost:8080"));
// after
store.putConfig(new ConfigEntry("myprofile", "http://localhost:8080"));

// Java
if ("default".equalsIgnoreCase(entry.getName())) { throw new IllegalArgumentException("use a named profile, not the default config"); }
store.putConfig(entry);

function isWritableProfile(name) { return typeof name === 'string' && name.length > 0 && name !== 'default'; }

try { store.putConfig(entry); } catch (IllegalArgumentException e) { if (e.getMessage().contains("can't be modified")) { entry = new ConfigEntry("myprofile", entry.getValue()); store.putConfig(entry); } else throw e; }

When it happens

Trigger: Calling putConfig() with entry.getName() equal to DEFAULT_CONFIG, or via `pulsar-shell --set-config default ...` style commands targeting the reserved profile name.

Common situations: Users trying to edit the implicit 'default' configuration shown by config list; scripts that write settings back under a name read from defaults; tooling that round-trips all config entries including the default one.

Related errors

• Cannot use stdin, -e/--execute-command and -f/--filename opt
• ${paramName} cannot be bigger than <${maxValue}>!
• ${paramName} cannot be less than or equal to <0>!
• The value of ${paramName} can't be empty
• ${name} cannot be less than <${min}>!

AI-assisted analysis of apache/pulsar@820761864e (2026-09-06). Data as JSON: /api/errors/7db9b48064721c62. Report an issue: GitHub.