software errors / problem solutions

How to install a package of a certain version in Arch Linux. How to roll back a package to a previous version

Posted by Alex On June 17, 2025

Contents Is it possible to roll back a package version in Arch Linux Local Arch Linux package cache Arch Linux packages of previous versions online How to install an Arch Linux package from a local file How to roll back the NVIDIA video driver version in Arch Linux How to roll back the kernel version in Arch Linux How to...

Error “Missing key 827C8569F2518CC677FECA1AED65462EC8D5E4C5, which is needed to verify signature” in Kali Linux (SOLVED)

Posted by Alex On May 30, 2025

When updating Kali Linux package files, for example with the following command: sudo apt update && sudo apt full-upgrade -y You may encounter an error: Get:1 http://mirror.kku.ac.th/kali kali-rolling InRelease [41.5 kB] Err:1 http://mirror.kku.ac.th/kali kali-rolling InRelease Sub-process /usr/bin/sqv returned an error code (1), error message is: Missing key 827C8569F2518CC677FECA1AED65462EC8D5E4C5, which is needed to verify signature. Fetched 41.5 kB in 1s (32.1...

How to restart KDE Plasma Desktop without rebooting your computer

Posted by Alex On May 27, 2025

What to do if KDE Plasma freezes It happens that the desktop environment stops working normally due to some internal bug – this can manifest itself in many different ways: just a black screen picture freezes and the computer does not respond to the keyboard and mouse black background with the inability to select an application window and click the...

How to disable MSI laptop glow (Mystic Light) in Linux (without 3rd party software and without installing services)

Posted by Alex On May 3, 2025

Contents 1. Managing SteelSeries on Linux 2. How to disable backlighting for MSI laptops 3. OpenRGB to disable the SteelSeries Mystic Light 4. Disabling Mystic Light in Linux without third-party tools (using udev rules) 4.1 Hardware identification 4.2 Manually stopping the Mystic Light 4.2.1 Enabling auto suspend mode 4.2.2 Unbinding the driver 4.3 Creating a udev rule to keep Mystic...

Why GeForce RTX 50 series graphics card doesn't work in Linux (SOLVED)

Posted by Alex On April 30, 2025

Contents Blackwell architecture graphics cards in Linux Signs that the NVIDIA graphics card does not work in Linux Why NVIDIA GeForce RTX 5090, 5080, 5070, 5060 does not work in Linux How to install the NVIDIA GeForce RTX 5090, 5080, 5070, 5060 driver on Linux The NVIDIA Open driver is installed, but NVIDIA GeForce RTX 5090, 5080, 5070, 5060 does...

How to list all current connections to MySQL and MariaDB databases

Posted by Alex On April 15, 2025

Contents List of running operations and processes on MySQL and MariaDB server How to view MySQL and MariaDB processes in real time What do the fields in the SHOW PROCESSLIST output mean How to display MySQL and MariaDB process data row by row instead of in a table Alternative syntax for SHOW FULL PROCESSLIST How to display only certain columns...

PHP Fatal error: Uncaught mysqli_sql_exception: Too many connections in (SOLVED)

Posted by Alex On April 10, 2025

Contents Error “Uncaught mysqli_sql_exception: Too many connections” Why does the “Too many connections” error occur How to temporarily increase the maximum number of connections to MySQL / MariaDB How to permanently increase the maximum number of connections to MySQL / MariaDB What is the maximum number of connections that can be established for MySQL and MariaDB 1. Error “Uncaught mysqli_sql_exception:...

Error: failed retrieving file 'community.db' (SOLVED)

Posted by Alex On March 10, 2025

Starting from March 2025, during a normal system update, for example, using the following command: sudo pacman -Syu The error may appear: error: failed retrieving file 'community.db' from mirror.cyberbits.asia : The requested URL returned error: 404 In fact, the error is not critical and you can continue the update. However, let's figure out why this error occurs and how to...

Error “PHP Startup: session.sid_length INI setting is deprecated” (SOLVED)

Posted by Alex On February 13, 2025

After upgrading to PHP 8.4, you may have encountered the following error: PHP Deprecated: PHP Startup: session.sid_length INI setting is deprecated in Unknown on line 0 Deprecated: PHP Startup: session.sid_length INI setting is deprecated in Unknown on line 0 PHP Deprecated: PHP Startup: session.sid_bits_per_character INI setting is deprecated in Unknown on line 0 Deprecated: PHP Startup: session.sid_bits_per_character INI setting is...

Where does npm install packages? “Error: Cannot find module” even after installing the module

Posted by Alex On December 31, 2024

Contents “Error: Cannot find module” even after installing the module Where does node look for installed modules when specifying a relative path in the require() method Why does the error “Error: Cannot find module” occur when moving a .js file to another disk Where are the Node.js modules that I installed with npm How to check where the Node.js modules...