How to Fix “exec user process caused: exec format error” in Linux

Mar. 6, 2023



After completing a massive project, your team and you decided to use containerization for the entire project in the staging and production steps to avoid any environment-related issues and last-minute “it works on my machine” statements. But, while creating a container, you encountered the “exec user process caused: exec format error” and have no clue how to fix it. In this guide, we let’s dig into the possible reasons for the “exec user process caused: exec format error” this issue, along with some reliable fixes to solve it on your Linux system.

What Causes the “exec user process caused: exec format error”

What Causes the “exec user process caused: exec format error”

The newline character seems trivial and is often overlooked while troubleshooting, but it is known to be a major cause of some errors. The newline character is used to signify the “End Of Line” (EOL). This is interpreted differently by Windows and Linux. Windows uses CRLF (Carriage Return Line Feed), which interprets newline as\r\n. On the other hand, Linux uses LF (Line Feed), which interprets newlines as\n.

Suppose you wrote a file in Windows using the CRLF encoding, which when sent to staging or production with Linux as an environment causes the exec format error. This problem can be solved using some really simple steps:

  1. Open the file in theLinux text editorof your choice.

  2. Use the find-and-replace functionality or press Ctrl+F to search for “\r\n.” When found, replace it with “\n” everywhere.

  3. You can also set it to Linux encoding while writing code.

The system architecture mismatch is also one of the most common reasons for the “exec user process caused: exec format error“. The containerization technology was developed to solve software environment-related issues but not hardware ones.

For example, this usually happens when you’re working on projects on a system with ARM architecture, like with the newApple M-series chipsets. When you push a code to your production environment, which is using an x86 system, it results in the “exec user process caused: exec format error”. This is because every piece of code when converted to the lower level of instructions is different for both ARM and x86. Docker detects the Apple M1 Pro platform as “linux/arm64/v8“. To solve this problem, use the following docker syntax while building an image:

Then update your Docker file’s “FROM” statement using this syntax:

When you execute the above statements, your image will get modified from arm64 to amd64 architecture, fixing the issue at hand.

  1. Open the file you want the change the encoding for in VS Code.

  2. Go to the “File” menu in the top-left and hover your cursor over the “Preferences” option in the drop-down menu. Here, you need to select the “Settings” option from the sub-menu. Alternatively, you can directly press “CTRL + , (comma)” on the keyboard to access the Settings menu. This will open the settings menu in a separate tab.

  3. In the search bar, type “encoding” and press Enter. Here, you will see the “Files: Encoding” setting with a drop-down menu.

  4. Here,choose UTF-8from the drop-down menu. This will change the encoding format for all global files opened or modified using VS Code.

Generally, applying the UTF-8 encoding method works for most users. But if you’re still facing the error, you can try changing the encoding to UTF8+BOM using the same steps as mentioned above. Here, BOM stands for Byte Order Mark.

If you are using vim or any other command line-based text editor, it uses the system-wide encoding format. Check out this article onhow to enable UTF-8 support in Linux.

File Permissions are often overlooked while working on a project. Permissions are of three types – read, write, and executable. The last type is divided into three categories of users – owner, user, and group. Generally, if you run an executable file without the correct permissions, it will give a “Permission Denied” error. But, while containerizing a big project, even a single file without executable permissions can cause the “exec user process caused: exec format error”. To check the permissions for every file in the container, use the following steps:

  1. First, navigate to the container using the command:

  2. Then, to check the file permissions of every file in the directory, use the following command:

  3. To change permissions for a file to executable permission, use the following syntax:

And since one of the reasons for this error is the missing file permissions, you need to be extra aware with the same when you try to execute something that involves user permissions in one way or the other. Hence, a basic lesson onLinux file permissionsshould keep the problems at bay.

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