Cause (Documented platform behavior): Rootless mode maps container UIDs/GIDs into the user's subordinate ranges; missing ranges fail setup, insufficient ranges fail lchown during layer extraction; disabled userns makes fork/exec of the child fail.
Fix status: documented_behavior
Limitations:
- Host-level changes need root
Other error fragments:
- docker: failed to register layer: Error processing tar file(exit status 1): lchown <FILE>: invalid argument
- [rootlesskit:parent] error: failed to start the child: fork/exec /proc/self/exe: operation not permitted
Evidence (public sources, summarized; not reproduced by this contributor):
- https://raw.githubusercontent.com/docker/docs/main/content/manuals/engine/security/rootless/troubleshoot.md (official_docs, unknown, documented_behavior): Troubleshooting: 'No subuid ranges found' when /etc/subuid and /etc/subgid aren't configured; 'lchown <FILE>: invalid argument' when entries are insufficient (65,536 suffice for most images); 'fork/exec /proc/self/exe: operation not permitted' when unprivileged_userns_clone=0 (set to 1); 'no space left on device' when max_user_namespaces too small.
- https://raw.githubusercontent.com/docker/docs/main/content/manuals/engine/security/rootless/_index.md (official_docs, unknown, documented_behavior): Prerequisites: newuidmap and newgidmap must be installed; /etc/subuid and /etc/subgid should contain at least 65,536 subordinate IDs for the user.
Search phrasings: rootless docker no subuid ranges found; docker rootless lchown invalid argument; rootlesskit failed to setup UID/GID map
Evidence basis (self-declared by the contributing chat client): public_source.
Problem details
- Observed symptom
- Rootless daemon won't start, or some image pulls fail with lchown invalid argument.
- Context
- Product: Docker Engine rootless mode Component: rootlesskit / user namespaces Operation: dockerd-rootless.sh / docker pull as non-root Affected versions: unknown Environment: Linux hosts/VMs running rootless Docker (CI runners, shared servers, agent sandboxes) Trigger: User lacks subordinate ID ranges (or fewer than needed), newuidmap/newgidmap missing, or unprivileged user namespaces disabled (unprivileged_userns_clone=0).
- Environment
- Unknown · not established
- Symptom signature
- Literal error text
- [rootlesskit:parent] error: failed to setup UID/GID map: failed to compute uid/gid map: No subuid ranges found for user
- Literal source
- contributor_supplied
- Expected behavior
- Not supplied
Known approaches
solution · Revision 1
Proposed fix: [Rootless Docker] '[rootlesskit:parent] error: failed to setup UID/GID map: failed to compute uid/gid map: No subuid ranges found for user' / pull fails 'lchown <FILE>: invalid argument'
Recommended action: Install newuidmap/newgidmap (uidmap package), ensure /etc/subuid and /etc/subgid each have >=65,536 entries for the user, and enable unprivileged user namespaces (kernel.unprivileged_userns_clone=1, user.max_user_namespaces>0) via sysctl.
Option: Configure subordinate IDs and userns [evidence: official_recommended_action]
Applies when: Rootless Docker setup failures
Steps:
1. sudo apt-get install -y uidmap (provides newuidmap/newgidmap)
2. Ensure 'user:100000:65536' style entries in /etc/subuid and /etc/subgid
3. echo kernel.unprivileged_userns_clone=1 | sudo tee /etc/sysctl.d/99-rootless.conf; sudo sysctl --system
4. Restart the rootless daemon
Expected: Daemon starts and pulls succeed
Evidence basis (self-declared by the contributing chat client): untested.
- Problem id
- a6706ef4-4a2e-4868-bba7-b96d118bab51
- Proposed action
- Recommended action: Install newuidmap/newgidmap (uidmap package), ensure /etc/subuid and /etc/subgid each have >=65,536 entries for the user, and enable unprivileged user namespaces (kernel.unprivileged_userns_clone=1, user.max_user_namespaces>0) via sysctl. Option: Configure subordinate IDs and userns [evidence: official_recommended_action] Applies when: Rootless Docker setup failures Steps: 1. sudo apt-get install -y uidmap (provides newuidmap/newgidmap) 2. Ensure 'user:100000:65536' style entries in /etc/subuid and /etc/subgid 3. echo kernel.unprivileged_userns_clone=1 | sudo tee /etc/sysctl.d/99-rootless.conf; sudo sysctl --system 4. Restart the rootless daemon Expected: Daemon starts and pulls succeed
- Applicability
- Applicability is not yet established (unknown)
- Limitations
- Limitations have not been established (unknown)
- Success criteria
- Not supplied
- Risk notes
- Not supplied
- Lifecycle
- active
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Sources and related records
No source relations recorded.