Mintplex-Labs/anything-llm · error · Error

Key cannot start with 'system.'

Error message

Key cannot start with 'system.'

What it means

Thrown by SystemPromptVariables._checkVariableKey when key starts with 'system.'. The 'system.' namespace is reserved for built-in system variables supplied by the platform during prompt expansion, so a user-defined static variable with that prefix is rejected to avoid collisions.

Source

Thrown at server/models/systemPromptVariables.js:367

  /**
   * Internal function to check if a variable key is valid
   * @param {string} key
   * @param {boolean} checkExisting
   * @returns {Promise<boolean>}
   */
  _checkVariableKey: async function (key = null, checkExisting = true) {
    if (!key) throw new Error("Key is required");
    if (typeof key !== "string") throw new Error("Key must be a string");
    if (!/^[a-zA-Z0-9_]+$/.test(key))
      throw new Error("Key must contain only letters, numbers and underscores");
    if (key.length > 255)
      throw new Error("Key must be less than 255 characters");
    if (key.length < 3) throw new Error("Key must be at least 3 characters");
    if (key.startsWith("user."))
      throw new Error("Key cannot start with 'user.'");
    if (key.startsWith("system."))
      throw new Error("Key cannot start with 'system.'");
    if (checkExisting && (await this.get(key)) !== null)
      throw new Error("System prompt variable with this key already exists");

    return true;
  },
};

module.exports = { SystemPromptVariables };

View on GitHub (pinned to 526360e320)

Solutions

1. Rename the key to drop the 'system.' prefix (e.g. 'system_context' or 'app_context').
2. Use the built-in 'system.*' variables instead of redefining them as static entries.

Example fix

// before
SystemPromptVariables.create({ key: 'system.context', value: '...' });
// after
SystemPromptVariables.create({ key: 'app_context', value: '...' });

if (typeof key === 'string' && key.startsWith('system.')) {
  throw new Error("Keys cannot use the reserved 'system.' prefix");
}

const isNonReservedKey = (k) => typeof k === 'string' && !k.startsWith('system.') && !k.startsWith('user.');

When it happens

Trigger: POST/PUT /system/prompt-variables with a key like 'system.foo', 'system.context', or 'system.date'.

Common situations: An admin assumes 'system.' is the conventional prefix for platform-level variables and tries to register one.

Related errors

• Key cannot start with 'user.'
• Key is required
• Key must contain only letters, numbers and underscores
• Key must be less than 255 characters
• System prompt variable with this key already exists

AI-assisted analysis of Mintplex-Labs/anything-llm@526360e320 (2026-08-13). Data as JSON: /api/errors/9055d63728da0b1e. Report an issue: GitHub.