November 2020 - Page 21 of 66

Common Problems 119029

Ubuntu 14.04 LTS – apt update returns 404 from archive mirrors

🟠 High   ⏱ 5–30 min  Last verified: 19 May 2026 Affected versions: Ubuntu 14.04 LTS Ubuntu 14.04 Ubuntu 14.04.6 📖 ~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 […]

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Common Problems 118978

Ubuntu 14.04 LTS SSH Public Key Login Suddenly Fails

🟡 Medium   ⏱ 5–30 min  Last verified: 19 May 2026 📖 ~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 117631

Ubuntu 20.04 LTS Recurring ext4 Journal Errors on Reboot

🟠 High   ⏱ 5–30 min  Last verified: 20 May 2026 Affected versions: 20.04 LTS 📖 ~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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Common Problems 114097

RHEL 10 – DNF package install fails because repository GPG key is missing – Fix & Prevention

🟡 Medium   ⏱ 5–30 min  Last verified: 20 May 2026 Affected versions: RHEL 10 📖 ~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 Set Up iSCSI Initiator on Oracle Linux 8 — step-by-step Oracle Linux 8 tutorial on Progressive Robot

How to Set Up iSCSI Initiator on Oracle Linux 8

Introduction Setting up set up iscsi initiator on oracle linux 8 on a Oracle Linux 8 server is a common task for system administrators, DevOps engineers, and site reliability engineers. This guide explains how to Set Up iSCSI Initiator on Oracle Linux 8, with all the commands you need, the SELinux and firewalld considerations to […]

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How to Configure RACF Integration on IBM AIX 7.2 — step-by-step IBM AIX 7.2 tutorial on Progressive Robot

How to Configure RACF Integration on IBM AIX 7.2

Introduction IBM AIX 7.2 is the latest release of IBM’s enterprise-grade UNIX operating system, running on IBM Power Systems hardware. Known for its reliability, security, and performance in mission-critical environments, AIX 7.2 introduces enhanced virtualization, security hardening, and cloud integration features. This guide covers how to configure racf integration on ibm aix 7.2 on IBM […]

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How to Configure LDAP on Windows Server 2012 R2 — step-by-step Windows Server 2012 R2 tutorial on Progressive Robot

How to Configure LDAP on Windows Server 2012 R2

How to Configure LDAP on Windows Server 2012 R2 Lightweight Directory Access Protocol (LDAP) is the standard protocol used to access and manage directory services, including Active Directory Domain Services. Applications, scripts, and third-party systems use LDAP to search for users, authenticate accounts, and read or modify directory objects. Windows Server 2012 R2 supports LDAP […]

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Java Lock Example - ReentrantLock — step-by-step Programming tutorial on Progressive Robot

Java Lock Example – ReentrantLock

URL: https://www.progressiverobot.com/java-lock-example-reentrantlock/ Welcome to Java Lock example tutorial. Usually when working with multi-threaded environment, we use [synchronized for thread safety](/community/tutorials/thread-safety-in-java). Java Lock ![java lock, java lock example, ReentrantLock in Java, java locks](images/java-lock-example-reentrantlock-section-1.png) Most of the times, synchronized keyword is the way to go but it has some shortcomings that lead the way to inclusion of […]

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