Minecraft is one of the best virtual sandbox games today. It’s available on various major platforms, including Windows, Linux, and macOS. This game was created and runs through the Java programming language.
However, users have reported the jna-4.4.0.jar error. It’s an error code that pops up upon opening the Minecraft launcher. In this guide, we’ll show you what the jna-4.4.0.jar error is on Minecraft and how to fix it.
Read this article to learn more.
Table of Contents
What is the jna-4.4.0.jar Error?
As with other launcher errors, you’ll see the error message and some important information that you can use later to have an idea of solving this issue. Some users pointed out that it’s a software-related or a mod-related problem. Here’s what you can see in the error window:
“Failed to download file, the file contents differ from what was expected.
Filename on disk: jna-4.4.0.jar
Path: C:\Users\[owner account name]\Minecraft\Install\libraries\net\java\dev\jna-4.4.0.jar
In other words, the Minecraft launcher attempted to download game files (.jar files) and it found out that the game files are different or incompatible. This issue can show up on your computer due to several reasons:
- Incomplete Download of Game Files – Whether due to a bad internet connection or a built-in antivirus, it’s hard to download game files in these situations. Most of the time, you’ll lack certain files, which is hard to know at first but can cause the jna-4.4.0.jar Minecraft error.
- Corrupt or Faulty Mods – Some Minecraft mods on the internet can be outdated, corrupted, or faulty, depending on your source. Faulty mods can break the game which forces you to reinstall everything.
- Outdated Minecraft Launcher – The Minecraft launcher is an app that’s free and is regularly updated. However, there are cases where users forget to download the latest version of this app which can lead to the jna-4.4.0.jar issue.
If there is trouble loading data between the Minecraft server and the client, then you can also experience the “Failed to Synchronize Registry Data From Server” error.
How to Fix the “Failed to Download the File, the File Contents Differ From What Was Expected” Error
Before going straight to the fixes, you can first try to restart your computer and see if the problem is still there. Another quick fix is to update Minecraft using the Minecraft launcher. This way, you can install all patches that can fix the jna–4.4.0.jar error.
To update Minecraft from the Minecraft launcher, follow these steps:
- Launch the Minecraft Launcher on your computer.
- Log into your Minecraft account by entering your login credentials.
- Click Options and select Force Update on the Launcher Options window.
- Once the update is installed, wait for the launcher to restart. Then, re-enter your login details.
- Play a game and see if the error still exists.
If it still shows up despite updating the Minecraft launcher, proceed to these fixes below. Make sure to go over them individually to see which one works best.
Fix #1: Check the URL on the Error Message
As mentioned earlier, the error message will display some critical information to help you solve this Minecraft launcher error. The URL that’s included in the message will let you download the file and replace it in the file path shown.
To download the file and replace it via the indicated URL and file path, proceed to the steps below:
- Save a copy of the error message by either taking a photo of it using a smartphone or just taking a screenshot of it. This is to ensure that the file is saved on the right file path.
- Copy the indicated URL on the message and paste it into your computer’s default browser. A file will now be downloaded automatically.
- Copy the file and move it to the indicated file path on the error message.
- Once the file is replaced, restart the launcher and see if the error is solved.
Once this method doesn’t work, you can unzip the file in a similar folder. Then, you can check later on if you still see an error message.
Fix #2: Delete Corrupted Mods
Once you’ve been using a variety of mods for Minecraft, there’s a high chance that you’ll encounter faulty or corrupted versions. Although it gives you a personalized look at your game, you cannot appreciate it that much if the game cannot be opened. Deleting faulty mods can easily fix this issue.
To delete defective mods on Minecraft, follow these steps:
- Open your computer and launch Run by searching for it in the Search menu.
- Once it’s open, navigate to this file “C: \Users\%username%\AppData\Roaming\.minecraft”
- Move the old mod folder to the Recycle bin and run Minecraft again and see if it launches normally.
Corrupted Mods can also cause the dreaded “Minecraft LAN Not Working” error, so it is always good to regularly update them.
Fix #3: Exempt Minecraft from Windows Firewall
Many users are experiencing problems downloading critical game updates from the internet, especially when the Windows Firewall is in the way. Besides that, the firewall can also block important processes and can lead to the jna-4.4.0.jar error.
To exempt or whitelist Minecraft from Windows Firewall, do the following:
- Open your Windows computer and press the Win + I keys to open Windows Settings.
- Select Update & Security > Windows Security.
- Choose Firewall & Network Protection and click Allow an app through the firewall.
- Click Change Settings and select Allow Another App…
- Select the Browse button and select the Minecraft launcher from the list.
- Click Add and tick the checkboxes for both Public and Private.
- Select OK. Restart your device and see if the problem is solved.
Fix #4: Launch Minecraft via the Vanilla Launcher
If you want to play the standard version of Minecraft, you can use the Vanilla launcher as a temporary solution. Once you can open Minecraft using this tool, the problem might be related to the mods installed.
To launch Minecraft via the Vanilla Launcher, follow these steps:
- Run the Minecraft Vanilla launcher on your computer and select Play.
- Let the program run until the Create game screen window shows up.
- Next, close the launcher both on the desktop and the system tray.
- Launch the original Minecraft launcher and check if the issue still exists.
Fix #5: Set the Java Platform as a Default File Opening Preference
To open .jar files, you’ll need to use the Java runtime environment. However, sometimes it’s not set by default on some Windows computers. You can try selecting the file opening preference manually and check if this solves the Minecraft launcher issue.
To set the file opening preference to Java, follow the steps below:
- Go to Explorer > Local Drive C: > Users.
- Select your username folder and go to AppData > Roaming > .minecraft.
- Select any .jar file and right-click it. Click Properties.
- Next to the Opens With button, select Change and choose Java(™) Platform SE Binary.
- Click OK. Launch the Minecraft launcher and see if the game now opens smoothly.
Fix #6: Reinstall Minecraft
As your last resort, reinstalling Minecraft will download all original game files that might have been overwritten or corrupted during a mod install. It gives the game a fresh start and will solve most Minecraft errors.
Important: Since you’ll be reinstalling Minecraft, your game progress might be deleted, along with the current game files. You can manage to copy the Save folder first to avoid losing game progress while deleting all existing game files.
To reinstall Minecraft on your computer, follow these steps:
- Using the Search menu, go to Programs and Features and search for the Minecraft Launcher.
- Right-click on it and choose Uninstall.
- Next, navigate to your Local C: Drive and go to Users > %username > AppData > Roaming.
- Right-click into the .minecraft folder and choose Delete.
- Now that Minecraft has been uninstalled, go to Minecraft’s official download page and download the launcher that’s compatible with your computer.
- Install it and log into your Minecraft account. Check if you can now launch the game without any errors. Also, don’t forget to paste the Save folder into the game files.
Some users have experienced the “Failed to download file, the file contents differ from what was expected” error when playing Minecraft on PC. This error prevents you from playing the game unless the indicated game file is replaced with a new version. Hence, this guide can help you solve the jna-4.4.0.jar in the Minecraft launcher using easy-to-follow fixes.