Hacktoberfest 2026: the issues maintainers tagged for October, open and beginner-friendly. Browse Hacktoberfest issues

TypeError: Cannot read properties of null (reading 'Env')

Open
#992 5 comments 0 reactions 1 assignee View on GitHub

@v-Kaniska244 is already working on this.

Since Apr 29, 2025.

Assessment

This issue has not been assessed yet.

Description

Getting this error suddenly from CLI/Vscode/Cursor:

➜  devcontainer build --workspace-folder . --config .devcontainer/devcontainer.json --image-name=test
[3 ms] @devcontainers/cli 0.75.0. Node.js v20.12.2. darwin 24.3.0 arm64.
TypeError: Cannot read properties of null (reading 'Env')
    at o6 (/Users/jasondamour/.nvm/versions/node/v20.12.2/lib/node_modules/@devcontainers/cli/dist/spec-node/devContainersSpecCLI.js:393:20372)
    at process.processTicksAndRejections (node:internal/process/task_queues:95:5)
    at async y6 (/Users/jasondamour/.nvm/versions/node/v20.12.2/lib/node_modules/@devcontainers/cli/dist/spec-node/devContainersSpecCLI.js:467:2352)
    at async dw (/Users/jasondamour/.nvm/versions/node/v20.12.2/lib/node_modules/@devcontainers/cli/dist/spec-node/devContainersSpecCLI.js:467:1886)
    at async R7 (/Users/jasondamour/.nvm/versions/node/v20.12.2/lib/node_modules/@devcontainers/cli/dist/spec-node/devContainersSpecCLI.js:667:2203)
    at async S7 (/Users/jasondamour/.nvm/versions/node/v20.12.2/lib/node_modules/@devcontainers/cli/dist/spec-node/devContainersSpecCLI.js:666:4937)
    at async /Users/jasondamour/.nvm/versions/node/v20.12.2/lib/node_modules/@devcontainers/cli/dist/spec-node/devContainersSpecCLI.js:484:1188
{"outcome":"error","message":"Cannot read properties of null (reading 'Env')","description":"An error occurred building the container."}

With the dockerfile:

FROM mcr.microsoft.com/devcontainers/base:1.2-ubuntu-22.04

Given I haven't upgraded the CLI in a while and this was working fine recently, I believe this is caused by a change to the base Docker image. Semi-confirmed by changing my base image to ubuntu:22.04 and it worked fine.

However, going to use this repo for the issue. If an image doesn't have an Env property, shouldn't the CLI still succeed?

Dominant language
TypeScript
Stars
3k
Forks
461
Avg merge
18m
Merged PRs (30d)
5

Contributor guide

Open the contributing guide

First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

More from devcontainers/cli

All issues in devcontainers/cli

Similar issues

More TypeScript issues

Get new issues in your inbox

A short digest of beginner-friendly GitHub issues.