[Bug] Devcontainer setup is broken
Brief Issue Summary
When working to patch a bug here, I created a Codespace to work on it. The Devcontainer config is not working because of this error:
The following error occurred reading the devcontainer.json file - "After parsing a value an unexpected character was encountered: [. Path 'extensions', line 12, position 24."
CMake Tools Diagnostics
n/a
Debug Log
Here's the creation log from the codespace:
=================================================================================
2025-10-09 07:45:44.163Z: Configuration starting...
2025-10-09 07:45:44.173Z: Cloning...
====================================== ERROR ====================================
2025-10-09 07:45:44.183Z: The following error occurred reading the devcontainer.json file - "After parsing a value an unexpected character was encountered: [. Path 'extensions', line 12, position 24." Please see https://docs.github.com/en/enterprise-cloud@latest/codespaces/setting-up-your-project-for-codespaces/introduction-to-dev-containers#devcontainerjson for help configuring your file.
=================================================================================
====================================== ERROR ====================================
2025-10-09 07:45:44.187Z: Container creation failed.
=================================================================================
2025-10-09 07:45:44.193Z:
===================================== WARNING ===================================
2025-10-09 07:45:44.194Z: Creating recovery container.
=================================================================================
=================================================================================
2025-10-09 07:45:45.338Z: Creating container...
2025-10-09 07:45:45.376Z: $ devcontainer up --id-label Type=codespaces --workspace-folder /var/lib/docker/codespacemount/workspace/vscode-cmake-tools --mount type=bind,source=/.codespaces/agent/mount/cache,target=/vscode --user-data-folder /var/lib/docker/codespacemount/.persistedshare --container-data-folder .vscode-remote/data/Machine --container-system-data-folder /var/vscode-remote --log-level trace --log-format json --update-remote-user-uid-default never --mount-workspace-git-root false --omit-config-remote-env-from-metadata --skip-non-blocking-commands --skip-post-create --config "/var/lib/docker/codespacemount/workspace/vscode-cmake-tools/.devcontainer/devcontainer.json" --override-config /root/.codespaces/shared/merged_devcontainer.json --default-user-env-probe loginInteractiveShell --container-session-data-folder /workspaces/.codespaces/.persistedshare/devcontainers-cli/cache --secrets-file /root/.codespaces/shared/user-secrets-envs.json
2025-10-09 07:45:45.511Z: @devcontainers/cli 0.80.0. Node.js v18.20.6. linux 6.8.0-1030-azure x64.
2025-10-09 07:45:46.026Z: $alpine -c echo Container started
2025-10-09 07:45:46.048Z: Unable to find image 'mcr.microsoft.com/devcontainers/base:alpine' locally
2025-10-09 07:45:46.187Z: alpine: Pulling from devcontainers/base
2025-10-09 07:45:46.228Z:
[1A[2K
9824c27679d3: Pulling fs layer
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64460e5168e0: Pulling fs layer
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2025-10-09 07:45:46.229Z: ba79d01ae1c8: Pulling fs layer
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7add29b687fa: Pulling fs layer
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85553cdd1418: Waiting
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a63fa575778c: Waiting
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64460e5168e0: Verifying Checksum
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9824c27679d3: Verifying Checksum
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2025-10-09 07:45:46.333Z: 9824c27679d3: Download complete
[7B2025-10-09 07:45:46.337Z: [7A[2K
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ba79d01ae1c8: Downloading 538.7kB/206.1MB
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85553cdd1418: Download complete
[3B2025-10-09 07:45:46.477Z: [7A2025-10-09 07:45:46.477Z: [2K
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ba79d01ae1c8: Downloading 26.48MB/206.1MB
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[4B2025-10-09 07:45:46.693Z: [6A[2K
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ba79d01ae1c8: Download complete
[2B2025-10-09 07:45:47.782Z: [6A[2K
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[5B2025-10-09 07:45:48.691Z: [5A[2K
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2025-10-09 07:45:50.334Z: [2B2025-10-09 07:45:50.452Z: [2A2025-10-09 07:45:50.453Z: [2K
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ba79d01ae1c8: Pull complete
[2B2025-10-09 07:45:57.263Z: [1A2025-10-09 07:45:57.264Z: [2K
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[1B2025-10-09 07:46:00.094Z: [1A[2K
7add29b687fa: Pull complete
[1B2025-10-09 07:46:00.100Z: Digest: sha256:1f8a1ea669115b1c87835427e89f6278f58a934a2e3f20eca3af7b6366ee5af2
2025-10-09 07:46:00.102Z: Status: Downloaded newer image for mcr.microsoft.com/devcontainers/base:alpine
2025-10-09 07:46:00.528Z: Container started
2025-10-09 07:46:00.705Z: Outcome: success User: vscode WorkspaceFolder: /workspaces/vscode-cmake-tools
2025-10-09 07:46:00.712Z: devcontainer process exited with exit code 0
=================================================================================
2025-10-09 07:46:01.697Z: Running blocking commands...
2025-10-09 07:46:01.742Z: $ devcontainer up --id-label Type=codespaces --workspace-folder /var/lib/docker/codespacemount/workspace/vscode-cmake-tools --mount type=bind,source=/.codespaces/agent/mount/cache,target=/vscode --user-data-folder /var/lib/docker/codespacemount/.persistedshare --container-data-folder .vscode-remote/data/Machine --container-system-data-folder /var/vscode-remote --log-level trace --log-format json --update-remote-user-uid-default never --mount-workspace-git-root false --omit-config-remote-env-from-metadata --skip-non-blocking-commands --expect-existing-container --config "/var/lib/docker/codespacemount/workspace/vscode-cmake-tools/.devcontainer/devcontainer.json" --override-config /root/.codespaces/shared/merged_devcontainer.json --default-user-env-probe loginInteractiveShell --container-session-data-folder /workspaces/.codespaces/.persistedshare/devcontainers-cli/cache --secrets-file /root/.codespaces/shared/user-secrets-envs.json
2025-10-09 07:46:01.945Z: @devcontainers/cli 0.80.0. Node.js v18.20.6. linux 6.8.0-1030-azure x64.
2025-10-09 07:46:02.144Z: Outcome: success User: vscode WorkspaceFolder: /workspaces/vscode-cmake-tools
2025-10-09 07:46:02.159Z: devcontainer process exited with exit code 0
=================================================================================
2025-10-09 07:46:02.165Z: Configuring codespace...
=================================================================================
2025-10-09 07:46:02.165Z: Finished configuring codespace.
Additional Information
No response
@kaladron Thank you for reporting the issue here. We tried to reproduce this issue on VS Code 1.105.0 + Dev Containers 0.427.0. We downloaded Docker, and VS Code connected to Docker properly. Please refer to this video: repro.zip. We were unable to reproduce this issue. Could you help us recheck this issue? In order for us to investigate this further, could you provide us with a sample project and the detailed repro steps? Thank you.