Resolving Segmentation Fault (“Core dumped”) in Ubuntu

A Segmentation Fault  is a specific error triggered by the operating system’s memory protection system. It happens when a program tries to access a memory area it’s not permitted to, or when it attempts to use that memory incorrectly, like trying to write to read-only sections.

The phrase “Core dumped” indicates that when the crash occurred, the operating system saved a full snapshot of the program’s memory (known as a “core dump”) to a file on the disk. This file is crucial for debugging because it contains the exact state of the program at the moment it failed, including details like the call stack, variable values, and memory mappings.

Why Does “Segmentation fault (core dumped)” Happen?

Here are some frequent culprits:

• Crashing binaries when upgrading your system
• Programs attempting to access invalid memory locations
• Outdated or broken software packages
• Cache corruption that can occur during installation or updates
• Problems tied to specific software dependencies

[ Also Read: How To Debug a Bash Shell Script? ]

How to Fix Segmentation Fault in Ubuntu

Segmentation fault is when your system tries to access a page of memory that doesn’t exist. Core dumped means when a part of code tries to perform read and write operation on a read-only or free location. Segfaults are generally associated with the file named core and It generally happens during up-gradation.

While running some commands during the core-dump situation you may encounter with “Unable to open lock file” this is because the system is trying to capture a bit block which is not existing, This is due to the crashing of binaries of some specific programs.

You may do backtracking or debugging to resolve it but the solution is to repair the broken packages and we can do it by performing the below-mentioned steps:

Method 1: Fix Using the Command Line

Step 1: Remove the lock files present at different locations.

sudo rm -rf /var/lib/apt/lists/lock /var/cache/apt/archives/lock /var/lib/dpkg/lock and restart your system h.cdccdc 

Step 2: Remove repository cache.

sudo apt-get clean all

Step 3: Update and upgrade your repository cache.

sudo apt-get update && sudo apt-get upgrade

Step 4: Now upgrade your distribution, it will update your packages.

sudo apt-get dist-upgrade

Step 5: Find the broken packages and delete them forcefully.

sudo dpkg -l | grep ^..r | apt-get purge

Method 2: Fix Using Recovery Mode (GUI)

Step 1: Run Ubuntu in startup mode by pressing the Esc key after the restart. 

Step 2: Select Advanced options for Ubuntu

Step 3: Run Ubuntu in the recovery mode and you will be listed with many options.

Step 4: First select “Repair broken packages”

Step 5: Then select “Resume normal boot”

So, we have two methods of resolving segmentation fault: CLI and the GUI. Sometimes, it may also happen that the “apt” command is not working because of segfault, so our CLI method will not work, in that case also don’t worry as the GUI method gonna work for us always.

Prevention Tips

To prevent segmentation faults moving forward, keep these tips in mind:

• Make it a habit to regularly update and upgrade your system packages.
• Try not to interrupt installations or upgrades once they’ve started.
• Periodically clean out the repository cache to keep things tidy.
• Always use stable versions of your applications to minimize issues.

Final Thoughts

Facing a segmentation fault (core dump) can be quite frustrating, but it is not impossible. Using the CLI method or recovery mode, you can quickly fix the problem and get your system working properly again.

To minimize the chances of encountering this error in the future, make sure your system is always updated and take precautions when upgrading.