How to fix error code 25015 with access denied message during .NET Framework 2.0 setup

Recently, I saw a post on the MSDN .NET Framework Setup Forum indicating that a customer was having trouble getting the .NET Framework 3.0 to install on his system.

How to diagnose this error

The error log for the .NET Framework 3.0 setup (%temp%\dd_dotnetfx3error.txt) showed the following information:

[11/10/06,11:30:12] Microsoft .NET Framework 2.0: [2] Error: Installation failed for component Microsoft .NET Framework 2.0. MSI returned error code 1603
[11/10/06,11:30:36] WapUI: [2] DepCheck indicates Microsoft .NET Framework 2.0 is not installed.
[11/10/06,11:30:37] WapUI: [2] DepCheck indicates Microsoft .NET Framework 3.0 was not attempted to be installed.

Based on this information, I determined that the .NET Framework 2.0 setup was failing.  Then, I used the list of .NET Framework 3.0 setup log files to request additional information from the customer - specifically, the log file named %temp%\dd_netfx_retMSI*.txt.

When the customer sent me this log file, I found the following error that was causing the .NET Framework 2.0 setup to fail:

Error 25015.Failed to install assembly 'C:\WINDOWS\Microsoft.NET\Framework\v2.0.50727\Microsoft.VisualBasic.Vsa.dll' because of system error: The process cannot access the file because it is being used by another process.

In addition, the customer sent me a log file created by Filemon that indicated that setup failed when attempting to open this file with an access denied error.

How to workaround this error

Based on the above information, I made an educated guess that there was something wrong with the folder and file permissions on the customer's system.  Fortunately, he was able to use the following steps to resolve this issue and successfully install the .NET Framework 3.0:

  1. Use the SubInAcl tool described at to make sure that the Administrators group and the SYSTEM account both have permissions to folders under %windir% and registry hives under HKLM
  2. Run the cleanup tool described at to make sure any remnants of the .NET Framework 2.0 have been removed from the system
  3. Try again to install the .NET Framework 2.0 (or in this case, try again to install the .NET Framework 3.0, which will try to install the .NET Framework 2.0 behind the scenes)

Important caveats about error code 25015

Please note - error code 25015 during .NET Framework 2.0 setup is a catch-all for many types of errors.  Therefore, the solution described in this post will likely only work if you see error code 25015 and the system error message states that the file is being used by another process and/or access is denied.  Not all instances of the 25015 error code will be resolvable with these steps.

In coding terms, error code 25015 is the else block at the end of a big if statement.  As a result, it ends up being the error code displayed after .NET Framework 2.0 setup verifies that the error is not caused by any other known fusion return code (which are defined in the file corerror.h that ships in the .NET Framework 2.0 SDK).

The customer who encountered this problem also posted this item on his blog describing this troubleshooting experience in case you are interested in reading that as well.  Hopefully this will be useful if you run into this type of error while installing the .NET Framework 2.0 on your system.