Problem setting up custom devcontainer in GitHub Codespaces

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Hi everyone,

I'm trying to set up a custom development environment in GitHub Codespaces using a .devcontainer/devcontainer.json file.

When I start the codespace, it builds the container but then fails to run my post-create commands. Here’s the error message I see:

[2025-09-27T15:32:45Z] Error: Command failed: npm install
npm ERR! code EACCES
npm ERR! syscall mkdir
npm ERR! path /home/codespace/.npm
npm ERR! errno -13

I've tried:

• Adding "remoteUser": "root" in my devcontainer.json.
• Setting permissions with RUN mkdir -p /home/codespace/.npm && chown -R codespace:codespace /home/codespace/.npm in my Dockerfile.
• Restarting the codespace multiple times.

Nothing has worked so far.

Has anyone faced this issue before or knows the proper way to fix this permissions problem in Codespaces?

Thanks!

[angelariasus]

You can fix this issue by clearing the npm cache and setting the correct permissions for the .npm folder.

Try running these commands inside your Codespace terminal:

mkdir -p ~/.npm
npm cache clean --force

If the error persists, update your devcontainer.json with this setting:

"remoteUser": "codespace"

Then rebuild the Codespace. This usually resolves permission issues.