If you’ve been working with Ubuntu 20.04 and encountered the “Invalid MIT-MAGIC-COOKIE-1 key” error when running programs, you’re not alone. This error typically occurs due to a permission problem or an issue with the magic cookie used for X11 authentication. This article will guide you through several potential solutions to this issue.
Understanding the Error
Before we dive into the solutions, it’s important to understand what this error means. The “MIT-MAGIC-COOKIE-1” is a type of authentication used by the X Window System, also known as X11 or simply X. When a client (a user-level program that requests the display of graphics) attempts to connect to an X server (the system-level software that provides the graphics), it needs to provide the correct “magic cookie” (a randomly generated key) to prove that it has permission to do so. If the keys don’t match, the server denies the connection, resulting in the “Invalid MIT-MAGIC-COOKIE-1 key” error.
Solution 1: Allow Local Connections
The first, and simplest, solution to try is to allow local connections to the X server. This can be done by running the following command in the terminal:
xhost +local:The xhost command is used to add and delete host names or user names to the list allowed to make connections to the X server. The +local: option allows connections from all users on the local machine.
Solution 2: Change the DISPLAY Variable
If the first solution doesn’t work, the next step is to change the DISPLAY environment variable. This variable tells clients where to display their graphics. You can change it using the export command as follows:
export DISPLAY=:0In this command, :0 is the display number. If you’re not sure what number to use, you can typically find it by running the command echo $DISPLAY.
Solution 3: Check the XAUTHORITY Variable
The XAUTHORITY environment variable points to a file that contains the magic cookies for the displays that the user has access to. If this variable isn’t set, or if it’s pointing to the wrong file, you might encounter the “Invalid MIT-MAGIC-COOKIE-1 key” error.
To check if the XAUTHORITY variable exists, run:
echo $XAUTHORITYIf nothing is returned, you’ll need to create the variable and set it to the path of the .Xauthority file, which is typically located in the user’s home directory:
export XAUTHORITY=~/.XauthoritySolution 4: Use the -Y Parameter for SSH
If you’re encountering this error while trying to run a program over SSH, try using the -Y parameter instead of -X to enable trusted X11 forwarding. This allows the remote program to interact with the local X server:
ssh -Y user@hostnameIn this command, user is your username and hostname is the name of the machine you’re connecting to.
Solution 5: Remove the -X Parameter from SSH
If you’re still encountering the error when using SSH, it might be because the program is trying to pipe the internal X11 display through SSH to a remote computer. To prevent this, remove the -X parameter from the SSH command:
ssh user@hostnameDebugging
If none of these solutions resolve the issue, you can try running xauth list and hostnamectl status to gather more information about the problem. Additionally, you can use tools like strace to debug the program and understand the underlying cause of the error.
Conclusion
The “Invalid MIT-MAGIC-COOKIE-1 key” error can be a frustrating hurdle when working with Ubuntu 20.04, but with these solutions, you should be able to resolve it. If you’re still encountering issues, don’t hesitate to reach out to the Ubuntu community for help.
X11 authentication is a method used by the X Window System to verify the identity of clients requesting access to the X server. It involves the use of a "magic cookie," which is a randomly generated key that must match with the one stored on the server for the connection to be allowed.
To check the value of the "DISPLAY" environment variable, you can run the command echo $DISPLAY in the terminal. This will display the current value of the variable, which should have the format ":<display number>". If the value is empty or incorrect, you may need to set it manually using the export command.
To find the display number to use for the "DISPLAY" environment variable, you can run the command echo $DISPLAY in the terminal. The display number is typically represented as a single digit, such as ":0" or ":1". If you’re unsure, you can try using ":0" as the display number, which is the default for the main X server.
The "XAUTHORITY" environment variable points to the file that contains the magic cookies for the displays that the user has access to. It is used by the X Window System to authenticate the user and allow them to connect to the X server. If this variable is not set or is pointing to the wrong file, you may encounter the "Invalid MIT-MAGIC-COOKIE-1 key" error.
To enable trusted X11 forwarding when using SSH, you can use the "-Y" parameter instead of "-X" when connecting to the remote machine. For example, you can run the command ssh -Y user@hostname to establish the SSH connection with trusted X11 forwarding enabled. This allows the remote program to interact with the local X server.
To remove the "-X" parameter from the SSH command, you simply need to run the command ssh user@hostname without any additional parameters. By omitting the "-X" parameter, you prevent the program from attempting to pipe the internal X11 display through SSH to a remote computer, which may help resolve the "Invalid MIT-MAGIC-COOKIE-1 key" error.
