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Installing updates for the Microsoft .NET Framework 4 can take longer than expected in some scenarios

When you install an update for the Microsoft .NET Framework 4, the Native Image Generator (NGen.exe) uses a high percentage of the CPU cycles on the computer for a long time. This time varies with how many Native Images are installed on the computer.
Updates to the .NET Framework 4 require a complete regeneration of the Native Image Cache, a very time-consuming operation. For some computers, an interaction with previously installed Native Images may cause Native Image regeneration to take much longer than expected. Although this issue only affects setup times, the effect can be several minutes to tens of minutes. Computers that have more Native Images installed will see longer generation times.
To work around this problem for you, go to the "Here's an easy fix" section. If you prefer to fix this problem manually, go to the "Let me fix it myself" section.

Here's an easy fix

To fix this problem automatically, click the Download button. In the File Download dialog box, click Run or Open, and then follow the steps in the easy fix wizard.
  • This wizard may be in English only. However, the automatic fix also works for other language versions of Windows.
  • If you’re not on the computer that has the problem, save the easy fix solution to a flash drive or a CD, and then run it on the computer that has the problem.

For the Microsoft .NET Framework 4, 32-bit editionFor the Microsoft .NET Framework 4, 64-bit editionFor the Microsoft .NET Framework 4, Itanium edition

Let me fix it myself

To work around this problem, you may be able to reduce Native Image Generation times somewhat by forcing NGen.exe to generate new Native Images without regard for what was previously generated.

To improve regeneration times, immediately before you install the .NET Framework 4 update, open an elevated command prompt and run the following commands.

Important Run these commands immediately before you apply the update. Otherwise, these commands are less effective.

On a computer that is running a 32-bit Windows operating system
%windir%\\framework\v4.0.30319\ngen.exe update /force /queue

On a computer that is running a 64-bit Windows operating system
%windir%\\framework\v4.0.30319\ngen.exe update /force /queue

%windir%\\framework64\v4.0.30319\ngen.exe update /force /queue


Article ID: 2570538 - Last Review: 01/25/2016 14:05:00 - Revision: 6.0

Microsoft .NET Framework 4

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