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Troubleshooting

Common issues, debugging guides, and problem-solving tutorials

25 tutorials

A small rack server rests on a sunlit wooden desk alongside a mechanical keyboard, a coiled patch cable, and a face-down printed sheet of paper.

USN-8955-1 Fixes 5 Nginx CVEs. 24.04 Stays on 1.24.0.

USN-8955-1 patches five Nginx security flaws across Ubuntu releases. Here is how to audit configs, apply package updates, and verify server stability.

October 29, 2026

NginxtroubleshootingUbuntu

A closed notebook and a blank sticky note on a steel shelf, warm side light, no labels and no logos.

🔧 troubleshooting Intermediate

KSMBD Has No CVE Yet. One Count Is Six. Another Is Five.

Cyber Kendra counted six ZDI reports on Oct. 21 and 22. Another writeup counted five. As of Oct. 23, the KSMBD pair still had no CVE.

October 25, 2026 ⏱️ 15 minutes

Linuxkerneltroubleshooting

A closed laptop on a metal rack shelf beside a blank status printout and an unplugged power lead, cool room light, no logos.

🔧 troubleshooting Intermediate

The Zone Is europe-west2-b. The Note Said Region.

The Oct. 20 London outage started at 06:08 UTC. The first status line named the region. The power quote named zone b only.

October 21, 2026 ⏱️ 20 minutes

Google Cloudeurope-west2outage

Two blank paper printouts, one short and one long, beside unplugged ethernet cables and a closed laptop on a beige desk.

🔧 troubleshooting Intermediate

Two Azure Incidents. Don't Merge the Region Lists.

Azure's Sept. 29 Sweden Central AI outage ran about 5 hours 55 minutes. ExpressRoute issues started 20:30 UTC Sept. 30. Region counts: 18, or 19.

October 7, 2026 ⏱️ 25 minutes

AzureExpressRouteVPN Gateway

A server chassis with the side panel off and a GPU seated in the tray, cool white bench light, no vendor logos and no readable text on the board.

🔧 troubleshooting Intermediate

NVIDIA's Sept. 30 List: Four Driver Builds, Then Update

GamingOnLinux lists four safe NVIDIA Linux driver builds from the Sept. 30 bulletin. The high scores are local memory bugs. Guest drivers are a separate row.

October 2, 2026 ⏱️ 30 minutes

NVIDIAGPU driverLinux

Network cabinet with a firewall appliance and a laptop showing a command prompt, cool aisle lighting, no logos or readable IPs.

🔧 troubleshooting Intermediate

CISA's Friday Deadline Already Passed. Check FMC, NetScaler, and Fortinet Anyway

KEV added Cisco FMC CVE-2026-20079 (CVSS 10), Citrix NetScaler CVE-2026-19490, and Fortinet CVE-2025-25249. Federal due date was 12 September. PivotC2 does not care that you are not a .gov.

September 15, 2026 ⏱️ 35 minutes

CISAKEVCisco FMC

A rack of industrial computers with a Debian terminal on the KVM screen showing apt and systemctl output

🔧 troubleshooting Intermediate

RHEL to Debian: Debug the Migration CERN Just Committed To

CERN is moving 2,200+ accelerator machines to Debian 13. Here is how to troubleshoot the package, kernel, and service breakage that shows up when you leave RHEL.

September 4, 2026 ⏱️ 35 minutes

DebianRHELCentOS

Sysadmin desk with dual monitors showing DNS lookup terminals and a coiled network cable

🔧 troubleshooting Intermediate

DNS Resolution Failures: A Systematic Guide to Diagnosing and Fixing DNS Issues on Linux

Your server can't reach the internet but the network is fine? DNS is probably the problem. Here's a methodical approach to diagnosing and fixing DNS resolution failures.

August 31, 2026 ⏱️ 25 minutes

DNSLinuxtroubleshooting

Terminal screen showing Docker network diagnostic commands with green checkmarks and red X marks indicating connectivity test results

🔧 troubleshooting Intermediate

Docker Container Has No Internet? A Systematic Guide to Diagnosing and Fixing Network Issues

Your Docker container can't reach the outside world. Before you start randomly changing settings, follow this systematic diagnostic workflow to identify whether the problem is DNS, routing, firewall rules, or IP forwarding — and fix it correctly the first time.

August 12, 2026 ⏱️ 20 minutes

Docker networkingcontainer troubleshootingDNS resolution

Terminal screen showing SSH connection attempt with green text on dark background, network topology lines

🔧 troubleshooting Intermediate

SSH Connection Troubleshooting: A Systematic Guide to Debugging Remote Access Issues

From 'Connection refused' to 'Permission denied', here's a step-by-step diagnostic workflow for every common SSH failure on Linux servers.

August 5, 2026 ⏱️ 25 minutes

sshlinuxtroubleshooting

A Linux terminal window showing mdatp health command output with a warning icon, dark terminal green-on-black aesthetic with security alert styling

🔧 troubleshooting

Microsoft Defender for Endpoint on Linux Just Started Silently Disabling Itself — Here's How to Check Yours

A recent Microsoft Defender for Endpoint update leaves the agent disabled on Linux servers after reboot. If you haven't checked since your last patch cycle, your production fleet might be running without protection.

July 30, 2026

LinuxsecurityMicrosoft-Defender

A terminal screen displaying Linux performance monitoring tools like htop and iostat, with glowing green text against a dark background, rendered in a hacker aesthetic style

🔧 troubleshooting

Your Server Is Slow and You Don't Know Why — A Systematic Linux Performance Debugging Guide

When your Linux server feels sluggish but nothing is obviously broken, the standard toolkit can miss what's really happening. A methodical troubleshooting workflow that finds the bottleneck every time.

July 24, 2026

linuxperformancetroubleshooting

Terminal-style illustration for Linux Network Troubleshooting — a systematic diagnostic workflow from ping to tcpdump

🔧 troubleshooting Intermediate

Linux Network Troubleshooting: From ping to tcpdump — A Systematic Diagnostic Workflow

A step-by-step troubleshooting guide covering the full diagnostic workflow for Linux network issues, from interface checks to deep packet inspection with tcpdump.

July 12, 2026 ⏱️ 20 minutes

LinuxNetworkingTroubleshooting

A terminal-style illustration showing a Linux disk usage analyzer with colorful bar charts and directory tree, rendered in green-on-black terminal aesthetic

🔧 troubleshooting Intermediate

Linux Disk Full? A Systematic Guide to Finding and Fixing the Problem

When your server hits 90% disk usage at 2 a.m., you need a process, not panic. This guide walks through the exact commands and workflow to find what's eating your disk and reclaim space without breaking running services.

July 7, 2026 ⏱️ 15 minutes

Linuxdisk spacetroubleshooting

Linux terminal showing OOM Killer diagnostic output on a dark server screen

🔧 troubleshooting Intermediate

Linux OOM Killer: How to Diagnose and Prevent Out-Of-Memory Process Kills

A practical guide to understanding, diagnosing, and preventing Linux OOM Killer events on production servers — from reading kernel logs to configuring cgroup memory limits.

June 24, 2026 ⏱️ 20 minutes

OOM KillerLinuxMemory

Linux terminal displaying systemd service failure logs with red error messages on dark background

🔧 troubleshooting Intermediate

How to Fix Systemd "Failed to Start Service" Errors on Linux

A step-by-step troubleshooting guide for diagnosing and resolving systemd service startup failures on Linux servers, covering journalctl analysis, common error patterns, and practical fixes.

June 13, 2026 ⏱️ 20 minutes

systemdtroubleshootingLinux

🔧 troubleshooting

Out of Memory on Production: A Methodical Troubleshooting Workflow for Linux Servers

A hands-on guide covering configuration, troubleshooting, and best practices for out of memory on production: a methodical troubleshooting workflow for linux servers.

April 23, 2026

LinuxOOMMemory

🔧 troubleshooting

SSL/TLS Certificate Expiry: Averted Disasters and Automated Renewal Troubleshooting

A hands-on guide covering configuration, troubleshooting, and best practices for ssl/tls certificate expiry - averted disasters and automated renewal troubleshooting.

April 20, 2026

SSLTLSCertificates

🔧 troubleshooting

Docker Container Crash Loop: Diagnosing and Fixing Exit Code 1 and 137

A hands-on guide covering configuration, troubleshooting, and best practices for docker container crash loop - diagnosing and fixing exit code 1 and 137.

April 17, 2026

DockerTroubleshootingCrash Loop

🔧 troubleshooting

Troubleshooting High CPU Usage with perf: From Flame Graphs to Fix

A hands-on guide covering configuration, troubleshooting, and best practices for troubleshooting high cpu usage with perf - from flame graphs to fix.

April 13, 2026

LinuxperfCPU

🔧 troubleshooting

Nginx 502 Bad Gateway: A Systematic Troubleshooting Guide

A hands-on guide covering configuration, troubleshooting, and best practices for nginx 502 bad gateway - a systematic troubleshooting guide.

April 9, 2026

NginxTroubleshooting502 Error

🔧 troubleshooting

Linux Disk Space Crisis: Tools and Commands to Find What's Eating Your Storage

A hands-on guide covering configuration, troubleshooting, and best practices for linux disk space crisis - tools and commands to find what's eating your storage.

April 5, 2026

LinuxDisk SpaceTroubleshooting

🔧 troubleshooting

Linux Troubleshooting: Essential Commands and Techniques

Master Linux system troubleshooting with this comprehensive guide. Covers process monitoring, network diagnostics, disk analysis, and memory troubleshooting.

February 8, 2026

Linuxtroubleshootingsystem administration

Linux terminal showing log analysis with grep, awk, and visualization

🔧 troubleshooting

Log Analysis Techniques: Parsing and Monitoring Server Logs

Master Linux log analysis with grep, awk, journalctl, and specialized tools. Learn log parsing techniques, pattern recognition, and automated alerting for production server monitoring.

February 8, 2026

logsanalysisLinux

Network diagnostics terminal showing packet analysis and connectivity testing

🔧 troubleshooting

Network Diagnostics Guide: Essential Tools and Techniques

Master Linux network diagnostics with comprehensive coverage of ping, traceroute, netstat, ss, tcpdump, and Wireshark. Learn troubleshooting methodologies that quickly identify connectivity issues.

February 8, 2026

networktroubleshootingLinux