Invalid MemoryRequestContext.thread.id: expected string, got

Error message

Invalid MemoryRequestContext.thread.id: expected string, got ${typeof thread.id}

What it means

parseMemoryRequestContext reads the 'MastraMemory' entry from the RequestContext and validates its shape before memory features use it. This error is thrown when a thread object is provided in the memory request context but its `id` property is not a string. The library throws it because all downstream memory operations (thread lookup, message persistence) depend on a string thread id.

Source

Thrown at packages/core/src/memory/types.ts:163

  if (!memoryContext) {
    return null;
  }

  // Validate the structure
  if (typeof memoryContext !== 'object' || memoryContext === null) {
    throw new Error(`Invalid MemoryRequestContext: expected object, got ${typeof memoryContext}`);
  }

  const ctx = memoryContext as Record<string, unknown>;

  // Validate thread if present
  if (ctx.thread !== undefined) {
    if (typeof ctx.thread !== 'object' || ctx.thread === null) {
      throw new Error(`Invalid MemoryRequestContext.thread: expected object, got ${typeof ctx.thread}`);
    }
    const thread = ctx.thread as Record<string, unknown>;
    if (typeof thread.id !== 'string') {
      throw new Error(`Invalid MemoryRequestContext.thread.id: expected string, got ${typeof thread.id}`);
    }
  }

  // Validate resourceId if present
  if (ctx.resourceId !== undefined && typeof ctx.resourceId !== 'string') {
    throw new Error(`Invalid MemoryRequestContext.resourceId: expected string, got ${typeof ctx.resourceId}`);
  }

  return memoryContext as MemoryRequestContext;
}

export type MessageResponse<T extends 'raw' | 'core_message'> = {
  raw: MastraMessageV1[];
  core_message: CoreMessage[];
}[T];

type BaseWorkingMemory = {
  enabled: boolean;

View on GitHub (pinned to 75dd419e61)

Solutions

Ensure the object stored under the 'MastraMemory' RequestContext key has `thread.id` set to a non-empty string before the request runs.
Stringify numeric/other ids at construction: `thread: { id: String(row.id) }`.
If thread is optional, omit the whole `thread` key (set undefined) rather than passing a partial object without an id.
Call parseMemoryRequestContext yourself (or a typeof check) when constructing custom RequestContext entries to fail early with a clearer stack.

Example fix

// before
requestContext.set('MastraMemory', { thread: { id: 42 }, resourceId: 'user-1' });
// after
requestContext.set('MastraMemory', { thread: { id: '42' }, resourceId: 'user-1' });

Defensive patterns

Strategy: type-guard

Validate before calling

const ctx = requestContext?.get('MastraMemory');
if (ctx && ctx.thread != null && typeof ctx.thread.id !== 'string') {
  throw new TypeError(`thread.id must be a string, got ${typeof ctx.thread.id}`);
}

Type guard

function hasStringThreadId(ctx: unknown): ctx is { thread: { id: string } } {
  return typeof ctx === 'object' && ctx !== null &&
    'thread' in ctx && typeof (ctx as any).thread?.id === 'string';
}

Try / catch

try {
  const memCtx = parseMemoryRequestContext(requestContext);
  // use memCtx
} catch (err) {
  if (err instanceof Error && err.message.includes('thread.id')) {
    logger.error('Malformed memory context: thread.id is not a string', { err });
    return; // skip memory for this request or fix context upstream
  }
  throw err;
}

Prevention

Always construct thread ids with String(...) at the boundary where ids originate.
Set the 'MastraMemory' RequestContext entry only through helper APIs, not by hand.
Add a runtime schema check (zod) on context objects before storing them.
Never store partial thread objects; omit the key when there is no thread.

When it happens

Trigger: Calling any memory-consuming API (memoryContext, threadId, memoryRunState, getThreadId, resolveThreadId, memoryConfig) with a RequestContext whose 'MastraMemory' entry contains `thread` as an object whose `id` is not a string — e.g. `thread: { id: 123 }`, `{ id: undefined }`, `{ id: null }`, `{ }`, or a thread object deserialized from JSON where id became a number.

Common situations: Passing a numeric database primary key as thread id instead of stringifying it; building the context manually instead of via the memory helper APIs; serializing/deserializing context over HTTP where id type drifts; copying a thread object from a different ORM where id is a number or ObjectId.

Related errors

AI-assisted analysis of mastra-ai/mastra@75dd419e61 (2026-08-30). Data as JSON: /api/errors/2def34bb7c18645d. Report an issue: GitHub.