memory MCP: Error [ERR_MODULE_NOT_FOUND] Cannot find package 'zod'

Fix memory MCP Error [ERR_MODULE_NOT_FOUND]: Cannot find package 'zod'

TL;DR

The published package forgot to declare zod as a dependency. Install zod next to it (or wait for a fixed release). The server imports zod at startup, so the missing module kills it before the MCP handshake.

The exact error:

Error [ERR_MODULE_NOT_FOUND]: Cannot find package 'zod' imported from .../dist/index.js

Steps

1. Confirm the missing dependency

Run the server by hand:

npx -y @modelcontextprotocol/server-memory

Success check: it exits immediately with the Cannot find package 'zod' error, and nothing else. That confirms a packaging bug, not your config.

2. Install zod alongside the package

npm install -g zod @modelcontextprotocol/server-memory

or with pnpm:

pnpm add -g zod @modelcontextprotocol/server-memory

Success check: rerunning the server no longer mentions zod; it waits on stdin for the MCP handshake.

3. Restart the client

Fully restart Claude Desktop / Claude Code / Cursor so the server relaunches with zod resolvable.

Success check: the memory tools (create_entities, read_graph, search_nodes) appear and work.

When this applies

• @modelcontextprotocol/server-memory (or server-sequential-thinking) exits instantly with the zod module-not-found error.
• Fresh installs are affected; the published dependencies list only @modelcontextprotocol/sdk.

When it does not apply

• The server starts but read_graph fails with Structured content does not match the tool's output schema: data/entities/0 must NOT have additional properties. That is a schema-validation issue with extra fields in memory.jsonl; strip the non-standard properties from the stored entities.
• Tools fail with JSON parsing errors on Windows. Check the server version; that is a different bug.

Tool compatibility

• @modelcontextprotocol/server-memory npm package (affected published versions)
• @modelcontextprotocol/server-sequential-thinking (same bug)
• Node.js 18+, npx / pnpm dlx launchers
• Claude Desktop, Claude Code, Cursor, Continue

Why it happens

The package's bundled dist/index.js contains import { z } from "zod", but zod was never added to the published dependencies in package.json. npm/pnpm only install declared dependencies, so a fresh install has no zod to resolve and Node throws ERRMODULENOT_FOUND at import time, before any MCP code runs.

Edge cases

• If you install with npx -y (ephemeral cache), the manual zod install can be wiped on cache eviction; a global install of both packages is more durable.
• Do not confuse with the sibling startup failure from the mcp 2.0 SDK rename; that one names McpError, not zod.
• Once a release declares zod properly, the manual install becomes unnecessary; check the changelog before scripting it permanently.