Cannot add marketplace from some AzDO remotes, while fetch succeeds #1402
Description
Describe the bug
tl;dr;
/plugin marketplace add fails for our AzDO remote, but agent actually fetches the content just fine into %userprofile%.
Adding from different remotes works fine.
Adding from the local fetched repo (fetched by copilot during adding marketplace (!)) works fine.
Full repro (100% consistent)
>dir %userprofile%\.copilot\marketplace-cache
Volume in drive C is Windows
Volume Serial Number is 6809-A424
Directory of C:\Users\jankrivanek\.copilot\marketplace-cache
02/11/2026 10:41 AM <DIR> .
02/10/2026 06:33 PM <DIR> ..
0 File(s) 0 bytes
2 Dir(s) 1,286,167,797,760 bytes free
>copilot -i "/plugin marketplace add https://devdiv.visualstudio.com/DefaultCollection/DevDiv/_git/AITestAgent"
╭──────────────────────────────────────────────────────────────────────────────────────────────────╮
│ ╭─╮╭─╮ │
│ ╰─╯╰─╯ GitHub Copilot v0.0.407-1 │
│ █ ▘▝ █ Describe a task to get started. │
│ ▔▔▔▔ │
│ Pick a model with /model. Send this session to GitHub with /delegate, and Copilot will create │
│ a PR. Enter ? to see all commands. Copilot uses AI, so always check for mistakes. │
╰──────────────────────────────────────────────────────────────────────────────────────────────────╯
● 💡 No copilot instructions found. Run /init to generate a copilot-instructions.md file for this project.
✗ Failed to add marketplace: Failed to fetch git marketplace from the provided URL. Please verify that the URL and
reference are correct.
Total usage est: 0 Premium requests
API time spent: 0s
Total session time: 1m 12.901s
Total code changes: +0 -0
Resume any session with copilot --resume
>dir %userprofile%\.copilot\marketplace-cache
Volume in drive C is Windows
Volume Serial Number is 6809-A424
Directory of C:\Users\jankrivanek\.copilot\marketplace-cache
02/11/2026 10:47 AM <DIR> .
02/10/2026 06:33 PM <DIR> ..
02/11/2026 10:47 AM <DIR> https---devdiv-visualstudio-com-DefaultCollection-DevDiv--git-AITestAgent
0 File(s) 0 bytes
3 Dir(s) 1,285,974,487,040 bytes free
>copilot -i "/plugin marketplace add %userprofile%\.copilot\marketplace-cache\https---devdiv-visualstudio-com-DefaultCollection-DevDiv--git-AITestAgent"
╭──────────────────────────────────────────────────────────────────────────────────────────────────╮
│ ╭─╮╭─╮ │
│ ╰─╯╰─╯ GitHub Copilot v0.0.407-1 │
│ █ ▘▝ █ Describe a task to get started. │
│ ▔▔▔▔ │
│ Pick a model with /model. Send this session to GitHub with /delegate, and Copilot will create │
│ a PR. Enter ? to see all commands. Copilot uses AI, so always check for mistakes. │
╰──────────────────────────────────────────────────────────────────────────────────────────────────╯
● 💡 No copilot instructions found. Run /init to generate a copilot-instructions.md file for this project.
● Marketplace "code-testing" added successfully.
Use /plugin marketplace browse code-testing to see available plugins.
Logs
Not much helpful info in logs - but attaching.
process-1770803396116-1260.log
process-1770803222856-45756.log
Affected version
GitHub Copilot CLI 0.0.407-1
Steps to reproduce the behavior
Reproes just on specific repo - https://devdiv.visualstudio.com/DefaultCollection/DevDiv/_git/AITestAgent
Full repro output above
Expected behavior
Adding marketplace succeeds or gives actionable error
Additional context
No response