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How to Fix Windows System Error Code ERROR_78: A Step-by-Step Guide


If you’ve encountered Windows System Error Code ERROR_78, you’re not alone. This error can be frustrating and may disrupt your workflow, but the good news is that it is often straightforward to fix. In this step-by-step guide, I’ll walk you through everything you need to know to resolve this issue quickly and confidently.


What is Windows System Error Code ERROR_78?

Before diving into solutions, it helps to understand what ERROR_78 means. The ERROR_78 corresponds to the message:

"Filename or extension is too long."

This typically occurs when a file path or filename exceeds the system’s allowed character limit — Windows has a maximum path length of 260 characters, and surpassing this can lead to this error. It can happen during tasks like copying, moving, or opening files.


Why Does ERROR_78 Happen?

  • Long file names or deeply nested folders.
  • Legacy compatibility issues with older applications.
  • Paths exceeding Windows’ maximum length limit (260 characters).
  • Sometimes corrupted system files or misconfigured software can manifest this error in different scenarios.


Step-by-Step Guide to Fix ERROR_78

Let’s get practical and fix this issue!

Step 1: Identify the Problematic File or Folder

Often, the error message will indicate which file or folder is triggering ERROR_78.

  • Check the file path mentioned in the error.
  • Note if the filename itself is extremely long or if it’s the folder path that’s too deep.

Step 2: Shorten the File or Folder Name

One of the easiest fixes is shortening the filename or folder names:

  • Right-click the file/folder → select Rename.
  • Reduce the length by abbreviating words or removing unnecessary characters.
  • Example: Change ThisIsAnExtremelyLongFolderNameThatExceedsWindowsLimit to ShortFolder.

Step 3: Move the File to a Root Directory

Sometimes, the deep folder structure causes the path to be too long. Moving the file closer to the root directory can help:

  • Cut the problematic file/folder.
  • Paste it directly into C:\ or another root-level folder.
  • Try accessing or operating on the file again.

Step 4: Enable Long Path Support in Windows 10/11

Windows 10 and 11 have a group policy setting to support long file paths. If you’re comfortable tweaking system settings, follow this:

For Windows 10 Pro/Enterprise:

  1. Press Win + R, type gpedit.msc, and press Enter.
  2. Navigate to:

    Local Computer Policy > Computer Configuration > Administrative Templates > System > Filesystem

  3. Find Enable Win32 long paths.
  4. Double-click it and set to Enabled.
  5. Click OK and restart your PC.

For Windows Home Edition:

  • This option is unavailable by default but can be enabled by editing the registry (be sure to backup your registry first).

  1. Press Win + R, type regedit, and press Enter.
  2. Navigate to:
    HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\FileSystem
  3. Find or create a DWORD value named LongPathsEnabled.
  4. Set its value to 1.
  5. Restart your PC.

Step 5: Use Command Prompt to Rename or Move Files

If Explorer won’t let you rename or move files due to this error, try Command Prompt:

  1. Open Command Prompt as Administrator (Win + X → Command Prompt (Admin)).
  2. Use the rename or move commands with a shorter path. Example:

    bash
    move "C:\very\long\path\to\file.txt" "C:\file.txt"

  3. After moving or renaming, try accessing the file normally.

Step 6: Check for Corrupted System Files

System errors sometimes coexist with file corruption.

Run System File Checker:

  1. Open Command Prompt as Administrator.
  2. Type:

    sfc /scannow

  3. Wait for the scan to complete and follow any prompts to fix corrupted files.

Step 7: Update Your Software and Windows

Sometimes the error arises from software incompatibility or outdated Windows components:

  • Check for Windows updates: Settings > Update & Security > Windows Update.
  • Update any apps that trigger the error, especially file explorers or backup utilities.


Bonus Tips to Avoid ERROR_78 in the Future

  • Limit folder nesting depth and filename length.
  • Use descriptive but concise file names.
  • Regularly clean up files and folders.
  • Consider using third-party tools that support long paths (like 7-Zip for archiving).


Final Thoughts

Encountering ERROR_78 can initially feel like hitting a wall, but with these straightforward steps, you can regain control of your files and prevent this error from interrupting your work again. If you’re unsure or uncomfortable performing some steps (like registry edits), don’t hesitate to seek professional help.

Feel free to bookmark this guide, and share it with friends or colleagues who might face the same issue — a little help goes a long way!


Did this guide help you fix ERROR_78? Let me know your experience or share any additional tips in the comments!


Keywords: Windows ERROR_78, how to fix error 78, Windows filename too long, system error code 78 fix, Windows long file path error

Updated on June 17, 2025
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