Failed to add marketplace" error when adding GitHub marketplace via Cowork plugin UI

[BrakTalk]

Environment:

Claude Desktop v1.1.5749 (ecf3d9)
Build date: 2026-03-08
Feature: Cowork → Plugins
MacOS

Steps to Reproduce:

1. Launch Claude Desktop
2. Navigate to the Cowork tab
3. Click "Customize with plugins"
4. Click Personal
5. Click +
6. Select "Add marketplace from GitHub"
7. Enter phuryn/pm-skills in the URL field
8. Click Sync

Expected Result:
Marketplace is added successfully and plugins from phuryn/pm-skills become available to install.
Actual Result:
A red error message is displayed: "Failed to add marketplace." No marketplace is added.
Screenshot: [attached]

Notes:

• The URL field accepts the owner/repo shorthand format (phuryn/pm-skills) as shown in the README for this marketplace, but it is unclear whether the app requires a full GitHub URL (e.g., https://github.com/phuryn/pm-skills) instead
• Suggested investigation: validate whether the input format, network access, or GitHub API rate limiting is the root cause
• I also tried the full URL since the README says to use full URL.
• It appears the Claude Desktop UI has changed a bit since this README was written.

[ConversationCommander]

Try to update Claude desktop. I had the same error and this worked for me.

'Help - Check for updates' or
'Help - Restart to update to x.x.x'