mastra-ai/mastra · critical · MastraError

MESSAGE_HISTORY_MISSING_STORAGE_ADAPTER

MESSAGE_HISTORY_MISSING_STORAGE_ADAPTER

Error message

Using Mastra Memory message history requires a storage adapter but no attached adapter was detected.

What it means

The lastMessages feature (recent message history recall) reads prior messages from storage. getInputProcessors throws this MastraError (MESSAGE_HISTORY_MISSING_STORAGE_ADAPTER, category USER, domain STORAGE) when lastMessages is configured but memoryStore is undefined when building the message-history input processor.

Source

Thrown at packages/core/src/memory/memory.ts:791

        processors.push(
          new WorkingMemory({
            storage: memoryStore,
            template,
            scope: typeof effectiveConfig.workingMemory === 'object' ? effectiveConfig.workingMemory.scope : undefined,
            useVNext:
              typeof effectiveConfig.workingMemory === 'object' &&
              'version' in effectiveConfig.workingMemory &&
              effectiveConfig.workingMemory.version === 'vnext',
            templateProvider: this,
          }),
        );
      }
    }

    const lastMessages = effectiveConfig.lastMessages;
    if (lastMessages) {
      if (!memoryStore)
        throw new MastraError({
          category: 'USER',
          domain: ErrorDomain.STORAGE,
          id: 'MESSAGE_HISTORY_MISSING_STORAGE_ADAPTER',
          text: 'Using Mastra Memory message history requires a storage adapter but no attached adapter was detected.',
        });

      // Check if user already manually added MessageHistory
      const hasMessageHistory = configuredProcessors.some(p => !isProcessorWorkflow(p) && p.id === 'message-history');

      // Check if ObservationalMemory is present (via processor or config) - it handles its own message loading and saving
      const hasObservationalMemory =
        configuredProcessors.some(p => !isProcessorWorkflow(p) && p.id === 'observational-memory') ||
        isObservationalMemoryEnabled(effectiveConfig.observationalMemory);

      // Skip MessageHistory input processor if ObservationalMemory handles message loading
      if (!hasMessageHistory && !hasObservationalMemory) {
        processors.push(
          new MessageHistory({

View on GitHub (pinned to 75dd419e61)

Solutions

Attach a storage adapter to Memory config, e.g. storage: new LibSQLStore({ url: 'file:memory.db' }).
Or configure storage on the parent Mastra instance so Memory inherits it.
If history recall is not needed, remove the lastMessages option.

Example fix

// before
const memory = new Memory({ options: { lastMessages: 10 } });

// after
const memory = new Memory({
  storage: new LibSQLStore({ url: 'file:memory.db' }),
  options: { lastMessages: 10 },
});

Defensive patterns

Strategy: validation

Validate before calling

function assertLastMessagesStorage(memoryConfig) {
  if (memoryConfig?.options?.lastMessages && !memoryConfig?.storage) {
    throw new Error('lastMessages requires a storage adapter on Memory (or inherited from Mastra)');
  }
}

Prevention

Treat lastMessages and storage as a mandatory pair in Memory configs.
Set storage once on the Mastra instance and register Memory there.
Add startup validation that constructs Memory with production config before serving traffic.

When it happens

Trigger: Setting options.lastMessages to a number (or true) on a Memory instance that has no storage adapter attached directly or inherited from the Mastra instance, then running an agent turn that builds input processors.

Common situations: Adding lastMessages to an existing Memory after upgrade without adding storage; Mastra instance lacking storage; test scaffolding with options-only Memory.

Related errors

AI-assisted analysis of mastra-ai/mastra@75dd419e61 (2026-08-30). Data as JSON: /api/errors/1900aba634a29a50. Report an issue: GitHub.