4 Systems & infrastructure

28 entries match these filters

• 0402 Fix: WSL2 has no network or DNS does not resolve apt update hangs, ping works by IP but not by name, or nothing reaches the internet from Ubuntu while Windows is fine.… Intermediate · Fixes an error · Windows Article Windows administration · WSL 15 Oct 2026
• 0375 Fix: disk full, find what is eating the space A Linux filesystem reports 100 percent used or No space left on device. Find the culprit with df and du, check journals,… Intermediate · Fixes an error · Linux Article Alerting & dashboards · Disks, LVM & filesystems 15 Oct 2026
• 0399 Fix: running scripts is disabled on this system (execution policy) PowerShell refuses to run .ps1 files until the execution policy allows it. The usual fix is RemoteSigned for your own user; here… Beginner · Fixes an error · Windows Article PowerShell · Windows administration 15 Oct 2026
• 0322 Fix: user is not in the sudoers file sudo refuses because your account is not allowed to use it. Add the user to the sudo group (Debian, Ubuntu) or wheel… Beginner · Fixes an error · Linux, macOS Article Server hardening · Users, sudo & hardening 15 Oct 2026
• 0323 Fix: Failed to start service, how to read systemctl status and journalctl Job for x.service failed tells you only that the service did not start. The real reason is in systemctl status and journalctl… Beginner · Fixes an error · Linux Article Logs · Services & systemd 15 Oct 2026
• 0325 Fix: SSL certificate problem: unable to get local issuer certificate curl, git, pip or npm cannot chain the server's certificate to a root they trust. Usual causes: a corporate proxy that re-signs… Intermediate · Fixes an error · Linux, macOS, Windows Article Common errors · Making requests · TLS & certificates 15 Oct 2026
• 0326 Fix: too many open files A process hit its file descriptor limit, usually 1024. Raise it for the shell, the systemd unit or the user, fix a… Intermediate · Fixes an error · Linux, macOS Article Performance & tuning · Processes & ports · Services & systemd 15 Oct 2026
• 0333 Fix: permission denied while trying to connect to the Docker daemon socket Every docker command fails with permission denied on /var/run/docker.sock. The daemon is fine; your user is not allowed to use its socket.… Beginner · Fixes an error · Linux Article Docker basics · Docker fixes 15 Oct 2026
• 0334 Fix: port is already allocated docker run or docker compose up fails with Bind for 0.0.0.0:8080 failed: port is already allocated. Find what holds the port, another… Beginner · Fixes an error · Linux, macOS, Windows Article Docker fixes · Processes & ports 15 Oct 2026
• 0343 Fix: Connection refused and Connection timed out, what each one means Refused means the host answered and nothing is listening there. Timed out means no answer at all, usually a firewall or wrong… Beginner · Fixes an error · Linux, macOS Article DNS, IP addresses & ports · Firewalls 15 Oct 2026
• 0320 Fix: address already in use (EADDRINUSE) Something is already listening on the port your program wants. Find the process with lsof or ss, stop it or pick another… Beginner · Fixes an error · Linux, macOS Article Networking & firewalls · Node.js · Processes & ports 15 Oct 2026
• 0321 Fix: E: Unable to locate package / could not get lock /var/lib/dpkg/lock Two apt errors with simple causes: Unable to locate package means the package lists are stale or the name is wrong; could… Beginner · Fixes an error · Linux Article Packages & updates 15 Oct 2026
• 0316 Fix: command not found bash: something: command not found means the shell could not find a program with that name in any PATH directory. The usual… Beginner · Fixes an error · Linux, macOS Article Basics · Packages & updates 15 Oct 2026
• 0317 Fix: Permission denied when running a script (chmod +x) bash: ./script.sh: Permission denied means the file exists but you may not execute it. Usually the execute bit is missing; sometimes the… Beginner · Fixes an error · Linux, macOS Article Basics · Users, sudo & hardening 15 Oct 2026
• 0172 Fix: No space left on device Writes fail because a filesystem is full, out of inodes, or holding space for deleted files that are still open. Find which… Beginner · Fixes an error · Linux Article Disks, LVM & filesystems 15 Oct 2026
• 0186 Fix: Ansible UNREACHABLE! Failed to connect to the host via ssh Ansible could not open an SSH session to the host, so no task ran. The text after the colon tells you why:… Intermediate · Fixes an error · Linux, macOS Article Ansible · SSH & servers 15 Oct 2026
• 0190 Fix: Terraform Error acquiring the state lock Another run holds the lock on your Terraform state, or a crashed run left it behind. Find out who holds it, wait… Advanced · Fixes an error · Any system Article Terraform 15 Oct 2026
• 0142 Fix: ImagePullBackOff and ErrImagePull in Kubernetes The pod cannot start because the node failed to pull the container image. Read the "Failed to pull image" event to see… Intermediate · Fixes an error · Linux Article Troubleshooting 15 Oct 2026
• 0143 Fix: CrashLoopBackOff in Kubernetes The container starts, exits, and Kubernetes waits longer before each restart. Read the previous container's logs and its exit code to find… Intermediate · Fixes an error · Linux Article Troubleshooting 15 Oct 2026
• 0144 Fix: Pod stuck in Pending with “0/3 nodes are available: Insufficient cpu” The scheduler cannot find a node with enough unreserved CPU for the pod's request. Compare the request with node allocatable resources, then… Advanced · Fixes an error · Linux Article Troubleshooting · Workloads & services 15 Oct 2026
• 0145 Fix: OOMKilled (exit code 137) in Kubernetes A container used more memory than its limit and the kernel killed it. Confirm the reason, measure real usage, then raise the… Advanced · Fixes an error · Linux Article Troubleshooting · Workloads & services 15 Oct 2026
• 0160 Fix: Permission denied in a container on OpenShift because of the random UID A container that works under Docker or Kubernetes crashes on OpenShift with permission denied, because restricted-v2 runs it with a random non-root… Advanced · Fixes an error · Linux Article Troubleshooting 15 Oct 2026
• 0161 Fix: Error from server (Forbidden): … is forbidden: User … cannot … in OpenShift oc refuses a command with Error from server (Forbidden). The message names the user, verb, resource and project. Learn how to read… Intermediate · Fixes an error · Any system Article Cluster administration · Troubleshooting 15 Oct 2026
• 0167 Fix: Job for nginx.service failed because the control process exited with error code systemctl prints this when a service's start command exits with an error. The real reason is in journalctl; for nginx it is… Intermediate · Fixes an error · Linux Article Networking & firewalls · Services & systemd 15 Oct 2026
• 0112 Fix: TASK ERROR: cluster not ready – no quorum? The node is not part of a quorate cluster, so /etc/pve is read-only and guests cannot be started or changed. Restore the… Advanced · Fixes an error · Linux Article Clusters & high availability 15 Oct 2026
• 0127 Fix: “Requested operation is not valid: network ‘default’ is not active” A libvirt VM will not start because the virtual network it uses, usually the NAT network 'default', is stopped. Start the network… Intermediate · Fixes an error · Linux Article Basics 15 Oct 2026
• 0110 Fix: TASK ERROR: VM is locked (backup) A VM or container still carries a backup lock, usually after a backup was interrupted. Check that no backup is running, then… Beginner · Fixes an error · Linux Article Backup & restore · VMs & containers 15 Oct 2026
• 0111 Fix: can’t lock file ‘/var/lock/qemu-server/lock-VMID.conf’ – got timeout Another task is holding the VM's local lock file, so a new action timed out waiting for it. Find the running or… Intermediate · Fixes an error · Linux Article VMs & containers 15 Oct 2026