[Bug] SyntaxError: The requested module 'ajv' does not provide an export named 'Ajv'

[alexander-zuev]

Describe the bug

Running integration tests with @modelcontextprotocol/sdk version 1.11.4 raises a runtime error:

SyntaxError: The requested module 'ajv' does not provide an export named 'Ajv'

Downgrading to 1.11.3 resolves the issue.

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To Reproduce

Steps to reproduce the behavior:

1. Clone https://github.com/alexander-zuev/kollektiv-mcp
2. pnpm remove @modelcontextprotocol/sdk
3. pnpm add @modelcontextprotocol/sdk@1.11.4
4. pnpm run test

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Expected behavior

Integration tests should pass as they do with version 1.11.3.

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Logs

FAIL   integration  tests/integration/index.test.ts [ tests/integration/index.test.ts ]
SyntaxError: The requested module 'ajv' does not provide an export named 'Ajv'
Test Files  1 failed | 15 passed (16)
Tests  109 passed (109)

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Environment

• Cloudflare Worker
• Vitest test runner
• Node.js v23.6.0
• pnpm (latest)

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Additional context

• No direct import of ajv in the project.
• The SDK is used as a dependency; the error appears to be caused by an internal import or packaging change in 1.11.4.
• Pinning the SDK to 1.11.3 avoids the error.

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Workaround

Pin @modelcontextprotocol/sdk to version 1.11.3 in package.json:

"@modelcontextprotocol/sdk": "1.11.3"

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Please investigate if a packaging or ESM/CJS export change was introduced in 1.11.4 that affects ajv imports.

[bhosmer-ant]

Hi @alexander-zuev - thanks for this report. On my side things are working as expected (npm remove @modelcontextprotocol/sdk followed by npm add @modelcontextprotocol/sdk@1.11.4 upgrades without error), and unfortunately I'm unable to replicate your full setup locally to reproduce (dependency issues installing pnpm).

Here's some details that will hopefully help bisect what's going on on your side:

• 1.11.4 adds a dependency on ajv version 8.17.1 (package.json)
• there's a preexisting dependency on ajv version 6.12.4 from eslint (package-lock.json)

This means that 1.11.4 has two dependencies on ajv at different versions. Maybe this is wrongfooting pnpm? I'm not familiar with it but I'm assuming the remove/add steps should upgrade the necessary dependencies a la npm.

In a pinch we could downgrade ajv to only the version used by eslint - this might be a useful simplification of the SDK's dependencies - but we should definitely figure out what's going on in your setup first.

[alexander-zuev]

@bhosmer-ant Thanks for such a prompt reply!

You are right this could be an issue caused by pnpm which requires all dependencies to be explicitly added to projects dependencies. If that helps, I can confirm the following didn't help me fix the issue:

• using npm as package manager - facing the same issue
• adding ajv via pnpm add ajv

Crucially I can confirm I didn't have this issue before upgrading to 1.11.4. It can be a peculiar bug on my machine - I'll try to debug further.

[bhosmer-ant]

Ah interesting that using npm didn't fix - I'd reflexively suspect your local setup in that case, since npm "works on my machine" (and I haven't seen any other reports of this issue, though of course that's not definitive).

It makes sense that the issue doesn't appear before upgrading - 1.11.4 is the first version of the TS SDK that imports ajv directly (rather than as an eslint dependency).

Please keep me posted on your local debugging - one datapoint that might be interesting is how ajv shows up in your package-lock.json or the pnpm equivalent (https://github.com/alexander-zuev/kollektiv-mcp/blob/main/pnpm-lock.yaml?) when you upgrade to 1.11.4

[bhosmer-ant]

@alexander-zuev fyi we've downgraded the ajv used by the SDK to match the one used by eslint, but that shouldn't affect your issue one way or the other (since eslint is a dev-only only dependency). Reopening this until we get to the bottom of what's happening on your setup.