No Matching Version Found for @anthropic-ai/sdk: There Is No 1.x on npm (2026)

Quick Answer (2026)

npm error code ETARGET
npm error notarget No matching version found for @anthropic-ai/sdk@^1.0.0.
npm error notarget In most cases you or one of your dependencies are requesting
npm error notarget a package version that doesn't exist.

There is no 1.x of @anthropic-ai/sdk on npm. There never has been. Anthropic ships two SDKs under one brand on two unrelated version lines, and the Python one is a major version ahead:

anthropic on PyPI is at 1.5.0. Its 1.0.0 landed 20 August 2026.

@anthropic-ai/sdk on npm is at 0.125.0, published 10 September 2026, after 204 stable releases that have never left major 0.

So the fix is one character: drop the 1. Install @anthropic-ai/sdk@^0.125.0, or just npm install @anthropic-ai/sdk and let the registry pick.

Everything below is read directly from both registries and reproduced on npm 11.6.0 with Node 24.8.0, in September 2026.

Reproduce it in ten seconds

npm install @anthropic-ai/sdk@^1.0.0
# npm error code ETARGET
# npm error notarget No matching version found for @anthropic-ai/sdk@^1.0.0.

npm install @anthropic-ai/sdk@^0.125.0
# added 7 packages in 1s

The second command is the control. If it succeeds and the first fails, nothing is wrong with your network, your registry mirror, your auth or your lockfile. You asked for a version that does not exist.

That distinction matters because ETARGET looks like a lot of other npm failures. A private-registry misconfiguration, an expired token or a proxy in the way all produce noisy npm errors too. notarget is the specific one that means the registry answered you correctly and the answer was no.

Why the two SDKs are not merely offset

The instinct is to assume the Python and TypeScript SDKs track each other and one is simply lagging. They do not track each other at all. Read from PyPI and the npm registry on 13 September 2026:

Look at the third row. The TypeScript package is four majors ahead of the Python one, the opposite direction to the two rows above it.

That is the actual rule, and it is worth internalising because it kills the shortcut: a version number you read in one language tells you nothing about the other. Not the number, not even which side is higher. These are separate repositories with separate release histories that happen to share a product name.

The 0.125.0 collision

This is the part that catches careful people, because the number you land on is a real number in both ecosystems and means opposite things.

On PyPI, 0.125.0 is the release that supports Python 3.9. Everything from 1.0.0 onward requires 3.10 or newer. So on a Python 3.9 runtime, upgrading reports success and quietly settles on 0.125.0, because that is the newest release that still fits, and you never see 1.x at all.

Two ecosystems, one version string, and it is simultaneously "newest" and "legacy" depending on which registry you are talking to.

The caret trap that follows

Once you correctly pin a 0.x package, the range operator you are used to changes meaning. This is standard npm semver, not an Anthropic quirk, but it bites here specifically because you have just been moved from a 1.x mental model to a 0.x one.

^1.5.0     resolves to    >=1.5.0 <2.0.0-0      minor and patch
^0.125.0   resolves to    >=0.125.0 <0.126.0-0  patch only
~0.125.0   resolves to    >=0.125.0 <0.126.0-0  identical to the caret

On a 0.x package the caret only allows changes to the left-most non-zero digit, so ^0.125.0 and ~0.125.0 are the same range. Verified against the semver library directly: ^0.125.0 accepts 0.125.9 and rejects 0.126.0.

The practical consequence is that ^0.125.0 will not pick up 0.126.0. On a package releasing as often as this one, a caret you assumed was permissive is close to a hard pin, and you will stop receiving updates without any warning. If you want the minor bumps, say so:

{
  "dependencies": {
    "@anthropic-ai/sdk": "0.125.x || >=0.126.0 <1.0.0"
  }
}

Or accept the tight range deliberately and bump it on a schedule. Either is defensible. Drifting into it by accident is not.

It is not only the main SDK

The same shape appears twice more in the same toolchain, and both reproduce identically:

npm install @modelcontextprotocol/sdk@^2.0.0
# npm error notarget No matching version found for @modelcontextprotocol/sdk@^2.0.0.

npm install @anthropic-ai/claude-agent-sdk@^1.0.0
# npm error notarget No matching version found for @anthropic-ai/claude-agent-sdk@^1.0.0.

The MCP case is the one most likely to hit you, because the Python mcp package went 2.0.0 on 28 July 2026 and that migration was widely written up. The TypeScript SDK is still on 1.30.0. If you read a Python-side MCP 2.x migration note and carried the version number across, this is the error you get.

@anthropic-ai/claude-agent-sdk is at 0.3.270 as of 12 September 2026, and is a different package from @anthropic-ai/sdk with a different shape. Do not swap one for the other while trying to fix a version error.

How to pin, in order of preference

1. Do not pin a major you have not checked. npm install @anthropic-ai/sdk writes whatever is current, and that is correct nearly always.
2. If you pin, read the registry first. npm view @anthropic-ai/sdk version costs one second and is authoritative.
3. Never copy a version from a tutorial in another language. That is the whole cause of this error.
4. Check your lockfile after any range widening, because a 0.x caret is narrower than you expect.

npm view @anthropic-ai/sdk version
npm view @modelcontextprotocol/sdk version
npm view @anthropic-ai/claude-agent-sdk version

If an LLM or a tutorial told you 1.x

This error has become more common, not less, and the reason is worth naming. Assistants trained or grounded on Python migration material will confidently suggest @anthropic-ai/sdk@^1.0.0, because the Python package really did go 1.x and the announcement was loud. The TypeScript package's non-event is not announced anywhere, because nothing happened.

There is no document to read that says "the TypeScript SDK did not release a 1.0". Absence is not published. The registry is the only source of truth, and it answers in one command.