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Claude Code Issues / #26951

[BUG] Cowork macOS - Plugin install fails with HTTP 404, plugins.claude.ai does not resolve

Open 💬 21 comments Opened Feb 19, 2026 by larrylim

Preflight Checklist

  • [x] I have searched existing issues and this hasn't been reported yet
  • [x] This is a single bug report (please file separate reports for different bugs)
  • [x] I am using the latest version of Claude Code

What's Wrong?

Installing the Marketing plugin from the Cowork Marketplace fails with "Failed to install plugin." The plugin cache directory (~/.claude/plugins/cache/) is never created, and installed_plugins.json is never generated. The root cause is that Cowork's VM attempts to fetch plugin files from plugins.claude.ai, which does not resolve via DNS (curl: (6) Could not resolve host: plugins.claude.ai), while api.anthropic.com and claude.ai both resolve correctly to 160.79.104.10.

Local CLI installation outside the VM succeeds (claude plugin install marketing@knowledge-work-plugins → files correctly written to cache), but Cowork VM cannot access the host filesystem due to isolation, so the plugin remains invisible to Cowork.

What Should Happen?

The Marketing plugin should download successfully to the plugin cache, appear in the Installed plugins tab, and its slash commands should be available in Cowork conversations.

Error Messages/Logs

[error] [CustomPlugins] Failed to fetch remote plugins: Failed to fetch browsable plugins (HTTP 404)
[info] [EventLogging] Queuing event: marketplace_plugin_cli_error | metadata: { target_id: 'knowledge-work-plugins /marketing' }
[info] [LocalPluginsReader] Found 0 enabled local plugins (0 installed)
[info] [VMCLIRunner] Running: claude plugin marketplace add knowledge-work-plugins /marketing --cowork
[info] [MarketplacePluginManagerCLI] Marketplace refreshed: knowledge-work-plugins

DNS verification:

text
$ curl -v https://plugins.claude.ai
* Could not resolve host: plugins.claude.ai   ❌

$ nslookup api.anthropic.com → 160.79.104.10  ✅
$ nslookup claude.ai → 160.79.104.10          ✅

Steps to Reproduce

Open Claude Desktop → Enter Cowork mode

Go to Plugins → Marketplace

Find "Marketing" under knowledge-work-plugins

Click Install

UI shows "Failed to install plugin"

Verify: ls ~/.claude/plugins/cache/ → "No such file or directory"

Check log: tail ~/Library/Logs/Claude/main.log | grep plugin → HTTP 404 errors

Workarounds attempted (all failed for Cowork):

Clear cache + reset enabledPlugins + reinstall via UI → cache never created

Delete Cowork VM Bundle and Restart → same HTTP 404 error

Install via local CLI → success on host, but Cowork VM cannot see host filesystem

Install inside Cowork VM terminal → cannot run nested claude CLI

Claude Model

None

Is this a regression?

I don't know

Last Working Version

_No response_

Claude Code Version

1.1.3541 (1e65e4) 2026-02-18

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Terminal.app (macOS)

Additional Information

_No response_

View original on GitHub ↗

21 Comments

github-actions[bot] · 4 months ago

Found 2 possible duplicate issues:

  1. https://github.com/anthropics/claude-code/issues/26893
  2. https://github.com/anthropics/claude-code/issues/26948

This issue will be automatically closed as a duplicate in 3 days.

  • If your issue is a duplicate, please close it and 👍 the existing issue instead
  • To prevent auto-closure, add a comment or 👎 this comment

🤖 Generated with Claude Code

Kavya-24 · 4 months ago

I was facing the same issues. This fixed for me

  1. Upgraded the Claude Desktop version - Finally came on version 1.1.3770 - Was getting 404 before
  2. In my marketplace.json, there was a circular dependency when defining the plugin. If your plugin lives in the same repo as your marketplace.json, you should use './' or the relative path of the plugin in the marketplace.json file
Andy-HN · 4 months ago

Anthropic Plugins are not displayed in the Claude Cowork plugins screen. v2.1.12 (Claude Code)

I see this in the terminal when I do an nslookup;

nslookup plugins.claude.ai
Server: 194.168.4.100
Address: 194.168.4.100#53

** server can't find plugins.claude.ai: NXDOMAIN
ekesel888-byte · 4 months ago

Anthropic Plugins are not displayed in the Claude Cowork plugins screen.

regentshopau-ops · 4 months ago

I have the same issue. Claude Cowork not loading pluginpage #26951. What is the solution for this?

1337Reaper · 4 months ago

Same issue. When I run an nslookup plugins.claud.ai is a non-existent domain

riccardobellitto · 4 months ago

I have the same issue on Windows. How can we fix this?

mercierj · 4 months ago

same issue

bradleygirl · 4 months ago

same issue

legend-arie · 4 months ago

same

mercierj · 4 months ago

Solved by making more space available on my mac (like 12Go freed)

stu-dixon · 4 months ago

Same issue. So it looks like Anthropic need to actually create a DNS record for plugins.claude.ai ...and point it to the plugins?

shyamsuchak-acme · 4 months ago

This is what it shows on terminal when I do nslookup plugins.claude.ai

Server: cache1.service.virginmedia.net
Address: 194.168.4.100

*** cache1.service.virginmedia.net can't find plugins.claude.ai: Non-existent domain

CharlieBrown06 · 4 months ago

I can't success to display the plugins:
22:59Ton screenshot confirme exactement le bug décrit : les skeleton loaders (les cadres grisés animés) s'affichent indéfiniment, ce qui signifie que l'interface attend une réponse du serveur plugins.claude.ai qui ne répond jamais.
C'est bien le bug infrastructure côté Anthropic — rien à faire de ton côté, c'est bloqué au niveau DNS/réseau d'Anthropic.
Ce que tu peux faire en attendant le fix :

Attendre une mise à jour de Claude Desktop — c'est la seule vraie solution
Voter/suivre l'issue GitHub pour être notifié du fix : issue #26951
Contacter le support via support.anthropic.com pour signaler le problème — plus il y a de remontées, plus c'est prioritaire

<img width="1725" height="931" alt="Image" src="https://github.com/user-attachments/assets/c8bd17ba-fe91-4da8-bb29-926a43b33b4a" />

CharlieBrown06 · 4 months ago

<img width="1599" height="900" alt="Image" src="https://github.com/user-attachments/assets/41ee35ca-b556-45d2-b783-9604e0848089" />

mattstratton · 3 months ago

Still reproducing as of March 27, 2026 on macOS (Claude Desktop latest). plugins.claude.ai returns NXDOMAIN from multiple DNS resolvers.

Adding context that this isn't just blocking Anthropic's own marketplace plugins, it also blocks third-party marketplace plugins that depend on the plugin cache and sync infrastructure. We maintain a plugin marketplace for our team (timescale/marketing-skills) and our users can't install via the marketplace or keep plugins installed because the cache at ~/.claude/plugins/cache/ never populates.

The zip upload path is also broken for local installs due to the separate getPlugins schema validation bug (#24328), so there's currently no working install path for custom plugins in Cowork.

Would really appreciate an Anthropic team member acknowledging this since the issue has been open 5+ weeks with no official response.

angelachanc91-star · 3 months ago

Bug: Plugin install fails with SSL_ERROR_SYSCALL on macOS with Clash VPN (fake-ip mode)

Environment

  • macOS (MacBook Pro)
  • Claude Desktop: latest version
  • Plan: Pro
  • Network: Clash X Pro in Enhanced Mode

What's wrong
Plugin installation fails with "Failed to install plugin." in Cowork.

DNS resolves successfully but returns a fake-ip address
TLS handshake fails immediately after:

curl -v https://plugins.claude.ai
→ IPv4: 198.18.0.165
→ Connected to plugins.claude.ai port 443
→ TLS handshake, Client hello sent
→ LibreSSL SSL_connect: SSL_ERROR_SYSCALL in connection to plugins.claude.ai:443

claude.ai and api.anthropic.com both work fine on the same machine
with the same Clash configuration.

Root cause (suspected)
Clash's fake-ip mode intercepts DNS and returns a virtual IP
(198.18.x.x range). TLS handshake from Cowork's VM fails because
the VM network stack cannot complete the proxy tunnel through
fake-ip for this specific domain.

Related to #26951 but different — DNS resolves via fake-ip,
but TLS fails at syscall level rather than DNS not resolving at all.

Expected behavior
Plugin installs successfully.

Workaround
None found. Switching proxy nodes did not help.

harshalamber · 3 months ago

Happening for me as well, plugins.claude.ai or support.claude.ai not opening using multiple wifi

SHIP-IT-JEDD · 2 months ago

Still broken April 21, 2026 — dig @8.8.8.8 plugins.claude.ai returns NXDOMAIN from Cloudflare authoritative

yatki · 1 month ago

Still not working.

shams96 · 1 month ago

Hitting this same issue on [your OS, e.g. macOS/Windows]. Tried installing the Linear plugin from the Cowork marketplace and it fails every time with "Failed to install plugin." No cache directory is created. This makes Cowork's plugin marketplace completely unusable for me. Please prioritize a fix — plugin installation is a core feature.

this bug has a long history and needs to fixed and severity needs to upgraded