Backup Recovery

Common Problems 118544

Ubuntu 16.04 LTS nginx fails to start due to certificate chain error

🟠 High   ⏱ 5–30 min  Last verified: 23 October 2019 Affected versions: 16.04 📖 ~1 min read Table of contents Symptom & Impact Environment & Reproduction Root Cause Analysis Quick Triage Step-by-Step Diagnosis Solution – Primary Fix Solution – Alternative Approaches Verification & Acceptance Criteria Rollback Plan Prevention & Hardening Related Errors & Cross-Refs […]

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Common Problems 118118

Ubuntu 18.04 Hostname Mismatch Breaks sudo and Mail Alerts

🟡 Medium   ⏱ 5–30 min  Last verified: 23 October 2019 📖 ~1 min read Table of contents Symptom & Impact Environment & Reproduction Root Cause Analysis Quick Triage Step-by-Step Diagnosis Solution – Primary Fix Solution – Alternative Approaches Verification & Acceptance Criteria Rollback Plan Prevention & Hardening Related Errors & Cross-Refs References & Further […]

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Common Problems 112492

Windows Server 2019 – BitLocker recovery prompts after firmware updates – Fix & Prevention

🟠 High   ⏱ 5–30 min  Last verified: 23 October 2019 Affected versions: Windows Server 2019 📖 ~1 min read Table of contents Symptom & Impact Environment & Reproduction Root Cause Analysis Quick Triage Step-by-Step Diagnosis Solution – Primary Fix Solution – Alternative Approaches Verification & Acceptance Criteria Rollback Plan Prevention & Hardening Related Errors […]

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How to Configure Redis Sentinel on FreeBSD 12 — step-by-step FreeBSD 12 tutorial on Progressive Robot

How to Configure Redis Sentinel on FreeBSD 12

Introduction How to Configure Redis Sentinel on FreeBSD 12 is a core administration task for any FreeBSD 12 server operator. FreeBSD 12 ships with the 15.0-RELEASE kernel, ZFS as the default root filesystem, Capsicum capability sandboxing improvements, and an updated ports tree. Unlike Linux distributions, FreeBSD uses rc(8) for service management, pf for packet filtering, […]

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How to Set Up IPsec with StrongSwan on FreeBSD 12 — step-by-step FreeBSD 12 tutorial on Progressive Robot

How to Set Up IPsec with StrongSwan on FreeBSD 12

Introduction This guide explains how to Set Up IPsec with StrongSwan on FreeBSD 12 on FreeBSD 12. FreeBSD uses the pkg(8) binary package manager, rc.conf(5) for service startup configuration, and pf(4) as its primary packet filter. There is no SELinux or AppArmor — instead, FreeBSD provides the MAC (Mandatory Access Control) framework and Capsicum for […]

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How to Set Up Automatic Security Updates on Debian 9 — step-by-step Debian 9 tutorial on Progressive Robot

How to Set Up Automatic Security Updates on Debian 9

Introduction Deploying set up automatic security updates on debian 9 on a Debian 9 Stretch machine is straightforward thanks to Debian’s policy-compliant packaging. Unlike rpm-based distributions, Debian stores configuration helpers in /etc/default/, uses update-rc.d for older init scripts, and provides dpkg-reconfigure for interactive package configuration. This tutorial stays on the systemd path throughout. Prerequisites You […]

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Common Problems 118577

Ubuntu 16.04 LTS Docker daemon fails with cgroup driver mismatch

🟡 Medium   ⏱ 5–30 min  Last verified: 21 October 2019 📖 ~1 min read Table of contents Symptom & Impact Environment & Reproduction Root Cause Analysis Quick Triage Step-by-Step Diagnosis Solution – Primary Fix Solution – Alternative Approaches Verification & Acceptance Criteria Rollback Plan Prevention & Hardening Related Errors & Cross-Refs References & Further […]

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Common Problems 118017

Ubuntu 18.04 OOM Killer Terminates Database Service

🟡 Medium   ⏱ 5–30 min  Last verified: 21 October 2019 📖 ~1 min read Table of contents Symptom & Impact Environment & Reproduction Root Cause Analysis Quick Triage Step-by-Step Diagnosis Solution – Primary Fix Solution – Alternative Approaches Verification & Acceptance Criteria Rollback Plan Prevention & Hardening Related Errors & Cross-Refs References & Further […]

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Common Problems 115423

RHEL 7 – Unregistered Subscription Leaves Yum with No Repositories

🟡 Medium   ⏱ 5–30 min  Last verified: 21 October 2019 📖 ~1 min read Table of contents Symptom & Impact Environment & Reproduction Root Cause Analysis Quick Triage Step-by-Step Diagnosis Solution – Primary Fix Solution – Alternative Approaches Verification & Acceptance Criteria Rollback Plan Prevention & Hardening Related Errors & Cross-Refs References & Further […]

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How to Set Up DRBD on FreeBSD 12 — step-by-step FreeBSD 12 tutorial on Progressive Robot

How to Set Up DRBD on FreeBSD 12

Introduction Deploying set up drbd on freebsd 12 on a FreeBSD 12 machine differs from Linux in several important ways: packages come from the FreeBSD Ports Collection or the binary pkg repository, services are registered in /etc/rc.conf via sysrc(8), and firewall rules are written in pf.conf(5) syntax. This tutorial stays entirely within the standard base […]

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