Differences between Windows Patch GDR and QFE

When installing Windows patches, you will often see GDR or qfe in the patches. What do they mean? In the past, Microsoft has already assigned a level for the update system files in the patch. GDR indicates "Normal Distribution version", and QEF indicates "quick patch engineering update version" Quickfix engineering ). Among them, GDR update files are generally subjected to a large number of rigorous tests, so the patch stability is relatively high, while QFE update files generally do less tests, so the stability is not as good as GDR.

Windows patches are classified into two categories: one is known as the "Security Patch". These patch packages contain both GDR and QEF version update files, that is, two copies, key updates are usually released when a critical vulnerability is detected in Windows. The second type is called "hotfix". Generally, some non-critical updates only contain QFE version update files.

Why does the "Security Patch" contain the versions of the two update files? For example, you need to install a non-critical update that only contains the QFE file. If the old system file to be updated for this patch is already in the GDR version, the update program will automatically compare the version number of the new and old files, if the original GDR file version is higher than the QEF file version in the patch package, the QFE file in the patch package will be automatically disabled for updates, instead, the QEF file with the same version number as the original GDR file will be updated. So where can I find this QFE file with the same version number as the original GDR file? The actual file is already in the computer's hard disk, because the same version of QFE has been copied to the system for backup when the "Security Patch" containing the GDR file was last installed. This is why the "Security Patch" must contain both GDR and QFE copies.

For example, to install the KB896688 Patch, you must update the system file % SystemRoot % \ system32 \ MSHTML. DLL. Because the KB89668 patch is a "security patch", it contains both GDR and QEF versions of MSHTML. DLL copies, whose file descriptions are "xpsp_sp2_gdr.051004-1415" and "xpsp.051004-1419", respectively ". After the update program is executed, the installer automatically detects the MSHTML of the current system. DLL version. If you find that the original file is the GDR version, you will use the GDR version in the patch package to update it. If you find that the original file is the QEF version, it will be updated with the QFE version in the patch package. In either case, after the update, the new system file will be the new version 6.00.2900.2769 after the update, but there are only GDR and QFE.

Now, let's look back at the first example we mentioned in KB896688. Suppose that before we update the KB896688 patch, the original system file MSHTML. DLL is already the GDR version, then when updating the patch, it will be updated with the GDR version of The xpsp_sp2_gdr.051004-1415 version of MSHTML. DLL. At the same time, the update program copies the QEF file of xpsp.051004-1419 to the hard disk. The specific location is the $ hf_mig $ sub-folder under the Windows folder. Assuming that we need to install another non-critical patch that also requires MSHTML. DLL modification in the future, this patch will automatically detect which version of the QEF file we provide is higher than the xpsp_sp2_gdr.051004-1415. If your own QEF version is not as high as the xpsp_sp2_gdr.051004-1415 version, it will not be updated with their own QFE file, in Windows \ $ hf_mig $, the Standby xpsp.051004-1419 will be taken out and updated.

I remember someone asking if the $ hf_mig $ folder in Windows can be deleted. Now, after the above explanation, you should understand that it is better not to delete the Windows \ $ hf_mig $ folder. Although deleting this folder will not cause the system to crash immediately, once the above mentioned situation occurs, it may cause compatibility problems caused by system file version mismatch after installing a new patch. Therefore, do not delete the $ hf_mig $ folder easily.

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