mastra-ai/mastra · error

Could not create the session: ${message}. Try again.

Error message

Could not create the session: ${message}. Try again.

What it means

Wrapping error thrown in createDraftSessionMutation's catch: any failure from the underlying session-creation call is re-thrown as 'Could not create the session: <cause message>. Try again.' with the original attached as cause. It exists to give users a single actionable message while preserving the root-cause error for developers.

Source

Thrown at mastracode/factory-ui/src/ui/domains/chat/hooks/useCreateUserSessionFromDraft.ts:50

      // Activating the pack applies its models server-side, so only hand off a
      // model when the draft explicitly deviated from the selected pack.
      const modeKey =
        activeModeId === 'build' || activeModeId === 'plan' || activeModeId === 'fast' ? activeModeId : undefined;
      const packModelId =
        draftModelPackId && modeKey
          ? modelPacks.find(pack => pack.id === draftModelPackId)?.models[modeKey]
          : undefined;
      const handoffModelId = activeModelId === packModelId ? undefined : activeModelId;

      try {
        const session = await createUserSession(baseUrl, projectRepositoryId, {
          sessionId: draftSessionId,
          title: prompt,
        });
        return { session, prompt, factoryId, projectRepositoryId, activeModeId, handoffModelId, draftModelPackId };
      } catch (error) {
        const message = error instanceof Error ? error.message : 'Session creation failed';
        throw new Error(`Could not create the session: ${message}. Try again.`, { cause: error });
      }
    },
    onSuccess: ({
      session,
      prompt,
      factoryId,
      projectRepositoryId,
      activeModeId,
      handoffModelId,
      draftModelPackId,
    }) => {
      queryClient.setQueryData(queryKeys.userSession(session.sessionId), session);
      addCachedSession(queryClient, projectRepositoryId, session);
      queryClient.setQueryData<MastraDBMessage[]>(
        queryKeys.agentControllerThreadMessages(
          AGENT_CONTROLLER_ID,
          session.sessionId,
          session.sessionId,

View on GitHub (pinned to 75dd419e61)

Solutions

1. Read error.cause to see the underlying message and fix that root issue first.
2. Retry the mutation as the message suggests; if it persists, check server logs for the create-session endpoint status.
3. Confirm the user session is authenticated (cookies/credentials: include) and the factoryId/projectRepositoryId are valid.
4. Verify handoffModelId (when set) is permitted by the active model pack/policy.

Example fix

// before
try {
  session = await client.createSession({ ... });
} catch (error) {
  const message = error instanceof Error ? error.message : 'Session creation failed';
  throw new Error(`Could not create the session: ${message}. Try again.`, { cause: error });
}
// after
try {
  session = await client.createSession({ ... });
} catch (error) {
  console.error('session create root cause:', error); // inspect cause server/client side
  throw new Error(`Could not create the session: ${error instanceof Error ? error.message : 'Session creation failed'}. Try again.`, { cause: error });
}

if (!draftSessionId || !factoryId || !factorySessionState?.projectRepositoryId) throw new Error('Could not create the session. Reload the page and try again.');

function hasCause(e: unknown): e is Error & { cause: unknown } {
  return e instanceof Error && 'cause' in e;
}

try {
  await createDraftSessionMutation.mutateAsync(prompt);
} catch (error) {
  const root = (error as { cause?: unknown })?.cause;
  showToast(`Could not create the session: ${root instanceof Error ? root.message : String(error)}. Try again.`);
  // optionally inspect root for status-specific handling (401 -> re-login)
}

When it happens

Trigger: Any exception inside the mutation body after the readiness checks — server 4xx/5xx from the create-session request, network failure, or a thrown error from activating the pack / creating the session server-side.

Common situations: Expired or missing auth cookie causing 401 on session create; server rejecting a handoffModelId not allowed by policy; transient network drop mid-request; draft session already consumed.

Related errors

• Session configuration is not ready. Try again.
• Failed to load repository settings (${res.status})
• Token exchange failed: ${error}
• Failed to fetch user info from Auth0
• Token exchange failed: ${error}

AI-assisted analysis of mastra-ai/mastra@75dd419e61 (2026-08-30). Data as JSON: /api/errors/da622c2374cdcc39. Report an issue: GitHub.