mastra-ai/mastra · error · HTTPException

agent thread aborts are not supported by this Mastra core ve

Error message

agent thread aborts are not supported by this Mastra core version

What it means

The abort-thread handler checks that the agent instance implements abortThreadStream. Older core versions lack thread-level abort, so the server returns HTTP 501 Not Implemented rather than throwing an opaque TypeError. It signals the deployment's core is too old for this endpoint.

Source

Thrown at packages/server/src/server/handlers/agents.ts:2158

});

export const ABORT_AGENT_THREAD_ROUTE = createRoute({
  method: 'POST',
  path: '/agents/:agentId/threads/abort',
  responseType: 'json' as const,
  pathParamSchema: agentIdPathParams,
  bodySchema: abortAgentThreadBodySchema,
  responseSchema: abortAgentThreadResponseSchema,
  summary: 'Abort active agent thread run',
  description: 'Aborts the currently active stream run for a memory thread without changing thread subscriptions',
  tags: ['Agents', 'Streaming'],
  requiresAuth: true,
  requiresPermission: 'agents:execute',
  handler: async ({ mastra, agentId, resourceId, threadId, requestContext: serverRequestContext }) => {
    try {
      const agent = await getAgentFromSystem({ mastra, agentId, requestContext: serverRequestContext });
      if (typeof (agent as { abortThreadStream?: unknown }).abortThreadStream !== 'function') {
        throw new HTTPException(501, {
          message: 'agent thread aborts are not supported by this Mastra core version',
        });
      }

      const effectiveResourceId = getEffectiveResourceId(serverRequestContext, resourceId);
      const effectiveThreadId = getEffectiveThreadId(serverRequestContext, threadId);

      if (!effectiveThreadId) {
        throw new HTTPException(400, { message: 'threadId is required' });
      }

      if (effectiveResourceId) {
        const memory = await agent.getMemory({ requestContext: serverRequestContext });
        if (memory) {
          const thread = await memory.getThreadById({ threadId: effectiveThreadId });
          await validateThreadOwnership(thread, effectiveResourceId);
        }
      }

View on GitHub (pinned to 75dd419e61)

Solutions

Upgrade @mastra/core to a version with abortThreadStream support
Rebuild/redeploy the server so it binds the updated core
Check all @mastra/* versions are aligned after the upgrade (pnpm why @mastra-core / pnpm ls)

Example fix

// before
pnpm add @mastra/core@0.10.0
// after
pnpm add @mastra/core@latest && pnpm build && redeploy

Defensive patterns

Strategy: type-guard

Validate before calling

function agentSupportsAbort(agent: unknown): boolean {
  return typeof (agent as { abortThreadStream?: unknown })?.abortThreadStream === 'function';
}

Type guard

function supportsAbort(a: unknown): a is { abortThreadStream: Function } {
  return !!a && typeof (a as { abortThreadStream?: unknown }).abortThreadStream === 'function';
}

Try / catch

try {
  await abortThread(agentId, { resourceId, threadId });
} catch (e) {
  if (e?.status === 501) console.warn('Thread aborts unsupported on this core version; upgrade @mastra/core');
  else throw e;
}

Prevention

Gate abort UI behind a capability check on the agent object
Upgrade core before exposing abort endpoints in production
Restart/redeploy after core upgrades so the running server picks up new agent methods

When it happens

Trigger: Calling the agent thread abort endpoint (DELETE/POST on the thread abort route) against an agent without an abortThreadStream function — i.e. pre-abort-support @mastra/core.

Common situations: Upgraded server/playground but not core; running against an old mastra deploy; custom agent implementations missing the method.

Related errors

AI-assisted analysis of mastra-ai/mastra@75dd419e61 (2026-08-30). Data as JSON: /api/errors/9dce65f853441275. Report an issue: GitHub.