Linux Troubleshooting Toolkit
Fix failed services, full disks, permission errors, high load, OOM kills, DNS, and SSH problems with command-driven guides and prompts.
Top Linux errors
Start with the most common production issues and troubleshooting paths.
61 Linux error guides
A full library of command-driven fixes — networking, memory, storage, boot, systemd, packages, and auth.
A stop job is running for...
How to fix the Linux 'A stop job is running for...' slow-shutdown error: find the hanging unit, tune DefaultTimeoutStopSec and…
ALERT! UUID=... does not exist. Dropping to a shell!
How to fix the Linux initramfs 'ALERT! UUID=... does not exist. Dropping to a shell!' error: repair fstab/UUID mismatches after…
Argument list too long
How to fix the Linux 'Argument list too long' (E2BIG) error: understand ARG_MAX, use xargs and find -exec, split globs, and wor…
bad interpreter: No such file or directory
How to fix the Linux 'bad interpreter: No such file or directory' error: CRLF line endings, wrong shebang paths, missing interp…
Cannot assign requested address
How to fix the Linux 'Cannot assign requested address' (EADDRNOTAVAIL) error: bind to a missing IP, ephemeral port exhaustion…
chown: invalid user: '<name>
How to fix the Linux chown: invalid user error: the user does not exist in NSS, a typo, an unresolvable LDAP/SSSD account, or a…
Connection refused
How to fix the Linux 'Connection refused' error (ECONNREFUSED): diagnose closed ports, dead services, wrong bind address and fi…
Best Linux prompts
Use these prompts to turn symptoms, logs, and config into a structured troubleshooting plan.
Linux mdraid Software RAID Recovery
Recover from degraded or failed mdraid arrays — failed disk, missing member, resync stuck, replacing drives without losing data.
Linux OOM Kill & Memory Pressure Investigation
Diagnose OOM kills, memory pressure, swap thrashing, slab bloat, and cgroup memory limit failures on Linux servers from dmesg OOM banners and /proc data.
Linux `perf` & Flame Graph Profiling
Profile a Linux process with `perf record` and generate flame graphs to find CPU hotspots, off-CPU waits, and frequent stack patterns.
Linux Server Troubleshooting
Help diagnose CPU, memory, disk, network, and service issues on Ubuntu or RHEL servers from raw command output.
Free Linux tools
Validate, troubleshoot, or analyze your configuration before production changes.
Linux Error Guides hub
Cause → fix → validation → prevention for 61 common Linux errors.
Open the hubLinux runbook
Use a repeatable checklist for production troubleshooting.
A first-response checklist for a misbehaving Linux host.
- 1 Check failed services (systemctl --failed)
- 2 Review journal errors (journalctl -p err -xb)
- 3 Inspect disk and memory (df -h, free -h, dmesg | tail)
- 4 Check DNS and network reachability
- 5 Validate recent changes (packages, config, deploys)