mem0ai/mem0 · error · Error

Mem0 API key must be a string

Error message

Mem0 API key must be a string

What it means

The second branch of _validateApiKey() throws when apiKey is present but not a string — e.g. a number, object, or array. TypeScript types say string, but at runtime (JS callers, JSON configs, env coercion) a non-string can reach the client, and the header-building code would produce garbage auth, so the client rejects it up front.

Source

Thrown at mem0-ts/src/client/mem0.ts:114

const identityByCredentials = new Map<string, Promise<ClientIdentity>>();

export default class MemoryClient {
  apiKey: string;
  host: string;
  private organizationId: string | number | null;
  private projectId: string | number | null;
  headers: Record<string, string>;
  client: any;
  telemetryId: string;
  private initialized: Promise<void>;
  private identityCacheMax: number;

  _validateApiKey(): any {
    if (!this.apiKey) {
      throw new Error("Mem0 API key is required");
    }
    if (typeof this.apiKey !== "string") {
      throw new Error("Mem0 API key must be a string");
    }
    if (this.apiKey.trim() === "") {
      throw new Error("Mem0 API key cannot be empty");
    }
  }

  constructor(options: ClientOptions) {
    this.apiKey = options.apiKey;
    this.host = options.host || "https://api.mem0.ai";
    this.organizationId = null;
    this.projectId = null;
    this.identityCacheMax =
      options.identityCacheMax ?? IDENTITY_CACHE_MAX_DEFAULT;

    this.headers = {
      Authorization: `Token ${this.apiKey}`,
      "Content-Type": "application/json",
    };

View on GitHub (pinned to 001c235229)

Solutions

1. Pass the raw string: apiKey: String(process.env.MEM0_API_KEY).
2. Quote the value in JSON/YAML config files so it parses as a string.
3. If the key arrives as an object (e.g. {token}), extract the string field before constructing the client.

Example fix

// before
const client = new MemoryClient({ apiKey: config.mem0_key }); // config.mem0_key = 4815162342

// after
const client = new MemoryClient({ apiKey: String(config.mem0_key) });

const asApiKeyString = (v: unknown): string => {
  if (typeof v === 'string') return v;
  throw new Error(`apiKey must be a string, got ${typeof v}`);
};

new MemoryClient({ apiKey: asApiKeyString(config.mem0_key) });

const isStringApiKey = (v: unknown): v is string => typeof v === 'string';

When it happens

Trigger: Passing apiKey: 12345, apiKey: { token: '...' }, or a Buffer; reading the key from a JSON config as a number; a proxy layer forwarding the key as a non-string type.

Common situations: Numeric-looking keys stored unquoted in JSON/YAML; JWE/JWT objects passed where the raw string is expected; JS callers bypassing the TS types.

Related errors

• Provide text or metadata to update
• Mem0 API key is required
• Mem0 API key cannot be empty
• apiKey is required for Mem0Memory
• Either 'api_key' must be provided or TURBOPUFFER_API_KEY env

AI-assisted analysis of mem0ai/mem0@001c235229 (2026-08-15). Data as JSON: /api/errors/1eb6ca72fd45c6d9. Report an issue: GitHub.