The error "unarc.dll returned an error code: 11" is a common Windows installation problem that usually appears when installing large games, compressed software packages, or repacks. This error indicates that Windows is unable to extract or read the required installation files, often due to memory issues, corrupted archives, or damaged system components. Fortunately, there are several reliable methods to fix this problem and complete the installation successfully.
Method 1: Check Your RAM for Stability
A common cause of error code 11 is unstable or faulty memory.
Press Windows + R, type mdsched.exe, and press Enter
Select Restart now and check for problems
Let Windows Memory Diagnostic scan your RAM
Method 2: Increase Virtual Memory (Paging File)
Increasing your paging file can help if your system runs out of memory during installation.
Press Windows + R, type sysdm.cpl, and hit Enter
Go to Advanced → Performance Settings
Select Advanced → Virtual Memory → Change
Uncheck Automatically manage paging file size
Set:
Initial size: At least your RAM size
Maximum size: Double your RAM size
Click OK, then restart your PC
Method 3: Re-download or Re-extract the Installer
Files from untrusted sources or heavy-compressed repacks often trigger error code 11.
Try the following:
Download the installer again
Avoid heavily compressed repack versions
Use official or verified installation sources
Ensure the archive isn't corrupted (check with WinRAR/Test Archive)
If the installation files are damaged, this is the quickest fix.
Method 4: Disable Antivirus or Windows Defender Temporarily
Security software may falsely block extraction.
Open Windows Security
Go to Virus & threat protection
Disable Real-time protection temporarily
Run the installation again
Re-enable protection afterward
This prevents your antivirus from deleting or blocking unarc.dll-related components.
Method 5: Use an Automated DLL Repair Tool
If you prefer a simple and fast fix, an automated repair tool like PcGoGo DLL Fixer can detect corrupted DLLs and system issues that cause unarc.dll errors.
Download the Program
Download and install PcGoGo DLL Fixer
Run a Full System Scan
Open the program and click Scan
Let it detect DLL or system-related errors
Repair
Click Repair Now to restore damaged components
Restart PC
Restart your PC after the repair
This method is helpful when manual repairs fail or when the issue involves multiple DLL dependencies.
Method 6: Free Up Disk Space
A nearly full drive may cause this error.
Open File Explorer
Right-click the C: drive
Select Properties → Disk Cleanup
Check temporary files, system cache, and Recycle Bin
Click OK to remove unnecessary files
Ensure you have at least 20–30 GB of free space for large game installations
Method 7: Run SFC and DISM to Repair System Corruption
Corrupted system files can also trigger unarc.dll issues.
Run SFC:
Open Command Prompt (Admin)
Type:
sfc /scannow
Let the scan complete
Restart your PC
Run DISM (if SFC cannot repair files):
DISM /Online /Cleanup-Image /CheckHealth
DISM /Online /Cleanup-Image /ScanHealth
DISM /Online /Cleanup-Image /RestoreHealth
Restart afterward
Method 8: Install or Reinstall Visual C++ Redistributables
Some installations require specific Visual C++ packages.
Visit the official Microsoft download page
Install all Visual C++ Redistributables, especially 2005–2015
Restart your PC
If the error is caused by missing libraries, this will fix it
Method 9: Perform a Clean Boot
Some services or background programs may interfere with file extraction.
Press Windows + R, type msconfig, press Enter
Go to Services tab
Check Hide all Microsoft services
Click Disable all
Go to Startup tab → Open Task Manager
Disable all startup apps
Restart your PC
Try the installation again
Method 10: Reinstall Windows (Last Resort)
If nothing works, your system may be damaged beyond repair.
Reset Windows while keeping your files
Reinstall a fresh copy of Windows
This is the most reliable solution for persistent, system-wide corruption
What Causes Unarc.dll Error Code 11
This error can be triggered by multiple system or file-related issues, including:
Corrupted or incomplete installation files
Insufficient RAM or unstable memory
Low virtual memory
Antivirus interference blocking file extraction
Damaged unarc.dll or ISDone.dll
Low or insufficient disk space
System file corruption
Bad sectors or problems with the hard drive
Conclusion
The error "unarc.dll returned an error code: 11" usually appears during installation due to memory issues, damaged installation files, or system corruption. By checking your RAM, increasing virtual memory, re-downloading the installer, repairing system files, and using specialized tools, you can resolve the problem effectively. Start with the simpler solutions, and move to advanced methods if the error persists.
