More and more users who previously used the seventh and eighth versions of Windows on their computers decide to upgrade to the tenth modification, but the existing system cannot be upgraded to Windows 10. Quite often, they are faced with a very unpleasant situation when the process either does not start at all, or at a certain stage of execution (for example, upon reaching 25%) an error is generated stating that it is impossible to start Windows 10 on this computer.
As an additional description, the system reserved partition cannot be updated. What is the saddest thing is that no repeated launches of the installation help. Let's try to get rid of this error together and see how to solve such an unpleasant problem.the simplest methods. I would like to immediately warn all users, without exception, that they will have to, as they say, roll up their sleeves, since they will need to work with system tools - the disk management section and the command line, which many people dislike. Alas, there is no other solution.
Error "Unable to update system reserved partition": what's the problem?
If anyone does not know, with the so-called clean installation of any of the latest operating systems, the system independently reserves a certain amount of disk space for its own needs in case of emergency situations. In the "seven" it is about 100 MB, and in the "eight" - 350 MB. It is with this section that the problems arise. Whether the installer cannot access it, or whether something is wrong with the existing OS, is not known for certain. But it is in this situation that the installer reports that it is unable to update the partition reserved by the system.
Actions with the disk management utility
The partition itself, reserved by the operating system, is hidden and has no letter assigned to it for identification in Explorer or any other file manager. That is, it is impossible to see it without using specialized tools that allow you to manage disk partitions. So the first thing to do is to make it visible. Third party software products may not be used. To perform the necessary operations, you can get by with your own Windows tools.
First call the disk management applet by typing "Run" in the consolecombination diskmgmt.msc.

Now select the reserved partition, and then through the RMB menu, go to the item for changing the drive letter, then click the "Add" button and select an unoccupied letter from the list (best somewhere at the end of the alphabet, for example, "Y") and then save the installed options.
Actions in the command console
The next step is to run the command console (cmd) as an administrator.

In it, you must first set the takeown /f command for execution. /r /d y and wait for the system to finish processing your request. When all operations are completed, write three more commands in sequence:
- icacls. /grant administrators:F /t;
- attrib -h -s -r bootmgr;
- chkdsk Y: /F /X /sdcleanup /L:5000, where Y is the previously defined partition letter.

Again, wait for requests to finish processing, then just close the command console.
Finishing Upload Folder and Partition Letter
Now go to the "Explorer" (shortcut - combination Win + E), turn on the display of hidden objects in the view menu and go to the partition that appears, which will be marked with the letter assigned to it in the disk management applet.

Here is the Boot boot directory. You need to remove absolutely everything that is from it, leaving only the en-US and ru-RU directories.
Note: for complete deletion, it is best to use the Shift + Del combination, rather than placing all objects in the Trash first.
Now use the key combination that is convenient for you to restart or restart using the standard method from the Start menu. After that, you can repeat the system upgrade when starting from a removable media with a distribution kit. In theory, Windows 10 will install normally, and the message that the system reserved partition cannot be updated will no longer appear.
As a final step, when the new OS is ready to use, call the disk management partition again and delete the letter assigned to the backup partition using the same method that was described at the very beginning (there is a special button).
Additional Solutions
It is better not to pay attention to the solutions offered on the Internet regarding freeing up space in the system partition or disabling all kinds of cryptographic system services, since they will not give any effective effect anyway! But if the problem occurs when you try to install updates for the “ten” itself, you can deactivate the antivirus, rename the SoftwareDistribution directory by adding old to its name with a dot, free up space on the “C” drive by cleaning or removing unnecessary programs and large files, reduce level of control of user accounts UAC, etc.

In extreme cases, you can execute the set of commands presented above in the command line, then reboot the system and set a manual search for updates with their further installation.