Mintplex-Labs/anything-llm · warning · Error

Key is required

Error message

Key is required

What it means

Thrown by the internal _checkVariableKey helper when the key argument is falsy (null, undefined, or empty string). This is the first of several sequential validations on a variable key and runs on both create and update paths (update passes checkExisting=false). It enforces that a key is always supplied before format/length checks.

Source

Thrown at server/models/systemPromptVariables.js:357

        } else {
          result = result.replace(match, variable.value || match);
        }
      }
      return result;
    } catch (error) {
      console.error("Error in expandSystemPromptVariables:", error);
      return str;
    }
  },

  /**
   * 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. Always supply a non-empty key when creating or updating a variable.
2. Validate at the API boundary: reject requests with a missing/empty key with a 400.
3. Check downstream validators too: key must match ^[a-zA-Z0-9_]+$, be 3–255 chars, and not start with 'user.' or 'system.'.

Example fix

// before
await SystemPromptVariables.create({ value: 'x' });
// after
await SystemPromptVariables.create({ key: 'my_var', value: 'x' });

if (typeof key !== 'string' || key.trim().length === 0) {
  return res.status(400).json({ error: 'key is required and must be a non-empty string' });
}

function isValidVariableKey(key) {
  return typeof key === 'string' && /^[a-zA-Z0-9_]{3,255}$/.test(key)
    && !key.startsWith('user.') && !key.startsWith('system.');
}

When it happens

Trigger: Creating or updating a system prompt variable without a key field, or with key set to '' / null / undefined. The validator's default (key = null) means omitting the argument entirely also trips it.

Common situations: Request body omitted the key field; the UI submitted the form before the key input was filled; a refactor changed the field name so key became undefined; programmatic seed script forgot to set the key.

Related errors

• Invalid video id!
• Impossible to retrieve Youtube video ID.
• Filename is required!
• Invalid scope: ${JSON.stringify(v)}
• Content must be a non-empty string

AI-assisted analysis of Mintplex-Labs/anything-llm@526360e320 (2026-08-13). Data as JSON: /api/errors/29e05bc072936a42. Report an issue: GitHub.