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Fix Error 1327 on Windows 10: Full Guide

Guide 10-6245 · Updated · Step by step

Error 1327 on Windows 10 is a common installer error that says “Invalid Drive: X:� and usually appears when you try to install or update a program. The fix is to either correct the drive letter in the Windows Registry or replace the drive letter with the actual installation path, and this guide walks you through both methods step by step.

What Causes Error 1327?

Error 1327 occurs when the Windows Installer (MSI) package references a drive letter that does not exist on your system. This often happens after you:

  • Rename or remove a drive (for example, changing a USB drive from E: to F:)
  • Uninstall a program that used a secondary drive
  • Use a network drive that is not currently mapped
  • Install a program from a DVD or USB drive that is no longer present

The error text usually looks like: “Error 1327. Invalid Drive: E:\�. The drive letter shown is the one the installer expects to find, but Windows cannot see it.

Before You Start: Check the Drive Letter

First, confirm whether the drive letter in the error actually exists. Open File Explorer and look at “This PC�. If the drive is present, the problem might be a permission issue or a corrupted registry entry. If the drive is not present, you have two options:

  1. Reconnect the drive (if it is a USB or network drive) and assign it the same letter it had before.
  2. Edit the registry to replace the invalid drive letter with a valid one.

If you can reconnect the drive, do that first. It is the simplest fix and avoids registry edits.

Method 1: Change the Registry Value

The most reliable fix is to edit the Windows Registry to replace the invalid drive letter with a valid one. This is safe if you follow the steps exactly.

  1. Press Win + R, type regedit, and press Enter.
  2. Navigate to: HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion
  3. Look for a key named ProgramFilesDir or ProgramFilesPath. Right-click it and select Modify.
  4. Change the drive letter in the value data to a valid one (for example, change E:\ to C:\).
  5. Click OK and close the registry editor.

Then try installing the program again. If the error persists, the installer may be reading the drive letter from a different registry location, such as the program’s own key under HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall or under HKEY_CURRENT_USER\Software. Search the registry for the invalid drive letter using Ctrl + F (Find) and replace all occurrences.

Method 2: Use a Valid Drive Letter in the Installer

If the installer lets you choose the installation folder, you can often bypass the error by specifying a valid drive. For example, if the error says E:\ is invalid, choose C:\Program Files instead. This works for many installers that only check the drive letter at the beginning.

If the installer does not give you a choice, you can create a temporary drive letter that matches the one in the error. For instance, if the error expects E:\, you can map a folder to that letter using the subst command:

  1. Open Command Prompt as Administrator.
  2. Type: subst E: C:\Temp\FakeDrive (create the folder first if needed).
  3. Run the installer again. When done, remove the mapping with subst E: /D.

This trick works because the installer sees a valid drive letter, even though it points to a folder on your C: drive.

Common Problems and Mistakes

One common mistake is editing the wrong registry key. The error may be caused by a specific program’s registry entry, not the global ProgramFilesDir. Always search for the exact drive letter shown in the error.

Another issue is that the registry value has a trailing backslash or extra characters. Make sure you only change the drive letter and keep the rest of the path intact (for example, C:\Program Files).

If you are using a 64-bit version of Windows, you may also need to check the WOW6432Node key under HKEY_LOCAL_MACHINE\SOFTWARE. Some 32-bit installers read from there.

Finally, do not forget to restart the installer after making changes. The Windows Installer service caches some information, so a clean restart of the installation process is necessary.

What If the Error Still Appears?

If the registry edits do not help, try these additional steps:

  • Run the installer as Administrator (right-click → Run as administrator).
  • Disable User Account Control (UAC) temporarily, then re-enable it after installation.
  • Use the Windows Installer CleanUp utility to remove leftover entries for the program.
  • Check if the installer is 32-bit and you are running 64-bit Windows – sometimes the drive letter is hardcoded in the MSI file itself, and you may need to extract and edit the MSI with a tool like Orca (available in the Windows SDK).

Editing the MSI file is advanced, but it is the only solution when the drive letter is embedded in the package. You can open the MSI in Orca, find the Directory table, and change the Dir value for the problematic drive.

Preventing Future Drive Letter Errors

To avoid this error in the future, always install programs to the default C: drive unless you have a strong reason not to. If you do use a secondary drive, assign it a permanent drive letter (like D:) and avoid changing it. For network drives, use UNC paths (\server\share) instead of mapped letters when possible.

If you frequently use USB drives for installation, remember to use the same drive letter each time, or copy the installer to the local drive before running it.

Frequently Asked Questions

Is error 1327 dangerous?

No, it is not a virus or a sign of hardware failure. It is simply a configuration issue where the installer cannot find the drive it expects.

Can I ignore error 1327 and continue?

No, the installation will not proceed until the drive letter is fixed. You must resolve the error before the program can install.

Will editing the registry break my computer?

Editing the registry is safe if you only change the specific values mentioned and back up the registry first (File → Export). Do not delete keys or change other values.

Why does the error show a drive letter I never used?

The installer was created with a specific drive letter in mind, often from the developer’s build environment. If you are installing from a downloaded file, the letter may be hardcoded in the MSI.

Does this error occur on Windows 11?

Yes, the same error can appear on Windows 11, and the same fixes apply.

What if I don’t want to edit the registry?

You can try the subst trick or contact the software vendor for an updated installer. If the program is old, you may need to run it in compatibility mode.

Related

General steps for current mainstream versions; menus can differ by device and version. See the disclaimer or report an error.

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