How to Fix ISDone.dll and Unarc.dll Errors in Compressed Games (2025 Fix)

If you have ever tried to install a highly compressed game (like GTA V, Red Dead Redemption 2, or Cyberpunk 2077) from a repacker like FitGirl or Dodi, you have likely faced the nightmare of the ISDone.dll or Unarc.dll error.

The error message usually looks like this:

“An error occurred when unpacking: Unarc.dll returned an error code: -1” “ERROR: archive data corrupted (decompression fails)”

Good News: This is not a virus, and your game file is likely not corrupted. This error happens because your PC’s RAM (Memory) is getting overwhelmed by the intense decompression process.

Here are the 3 proven methods to fix it in 2025.

Method 1: The “Virtual Memory” Fix (90% Success Rate)

This is the most common solution. Since highly compressed games require huge amounts of RAM to unpack, we need to trick your Windows into using your Hard Drive as “Fake RAM” (Pagefile).

1. Press Windows Key + R on your keyboard.
2. Type sysdm.cpl and hit Enter.
3. Go to the Advanced tab and click the first Settings button (under Performance).
4. In the new window, go to the Advanced tab again.
5. Under Virtual Memory, click Change.
6. Uncheck “Automatically manage paging file size for all drives.”
7. Select your C: Drive.
8. Click Custom Size and enter these values:
   • Initial Size (MB): 4096
   • Maximum Size (MB): 16000 (If you have 8GB RAM or less)
9. Click Set, then OK, and Restart your Computer.

Now try installing the game again. It will likely work!

Method 2: The “Safe Mode” Installation

If Method 1 failed, your background apps (Chrome, Discord, Antivirus) are eating up the RAM needed for installation. Booting into Safe Mode stops them.

1. Hold the Shift key on your keyboard and click Start > Power > Restart.
2. Your PC will boot into a blue menu. Select Troubleshoot > Advanced Options > Startup Settings > Restart.
3. When the PC restarts, press 4 to enter Safe Mode.
4. Your screen will look weird (low resolution). Locate your game’s setup.exe and run it.
5. Since no background apps are running, the installation will finish without the DLL error.
6. Once done, restart normally to play.

Method 3: Re-Register the DLL Files (Command Prompt)

Sometimes, the DLL files are actually missing or unregistered in Windows.

1. Open the Start Menu, type CMD, right-click it, and select Run as Administrator.
2. Type the following commands one by one and hit Enter:
   • regsvr32 isdone.dll
   • regsvr32 unarc.dll
3. If you get a success message, try installing.
4. Note: If you get a “Module not found” error, you need to download ISDone.dll and Unarc.dll from a trusted source and paste them into your C:\Windows\System32 and C:\Windows\SysWOW64 folders first.

FAQ: Common Error Codes

• Error Code -1: General RAM failure. Use Method 1.
• Error Code -6: Read/Write error. Your Hard Drive might be full or corrupted. Run chkdsk /f in CMD.
• Error Code -11: Bad Archive. Re-download the torrent; the file is genuinely broken.

Next Step: Now that you fixed the error, test your PC with our list of [10 Highly Compressed Games Under 5GB].