I wanted to run pip install which is some python install-tool when I ran into an error regarding the registry key HKEY_CURRENT_USER\Software\Classes\{057C7771-F320-4C2A-A2EA-747945FA82F2} (the program iterates over all keys in the Classes sub-tree). When I try to open, edit, view its attributes, change permissions or delete the key with regedt32 (with admin privileges) a message box appears which reads: (summarized and translated from German)

Error opening key
Due to error the key [key name] can not be opened
Details: The system can't find the file

Doing a fast Google search I found that the key is somehow related to the application Fast Picture Viewer which in fact I had once installed. Does anybody know how to force delete that damn key? Thanks.

I found out that at least 5 other keys in the same directory show the same behaviour.


I found that the real key name is {057C7771-F320-4C2A-A2EA-747945FA82F2}\0

  • Did you try editing the permissions of that key and adding your account with Full Control, and/or taking ownership of it? Nov 13, 2014 at 19:43
  • I am not able to change permissions, it tells me that there is no data available.
    – VoidStar
    Nov 13, 2014 at 19:46
  • You are using an Administrator account and have ran regedit as an Administrator correct?
    – Ramhound
    Nov 13, 2014 at 19:54

2 Answers 2


Try it this way:

You may get the following error message when trying to delete a registry key:

"Error while deleting key"

This can be caused if you attempt to delete a registry key that contains embedded null characters. These characters are not visible when viewing the registry entry. To delete a registry key that contains an embedded null character, you must first replace the null character with another character. You can accomplish this by using the RegDelNull tool from Sysinternals. This tool is available from the following URL.


Looks like your file that contains that part of registry is damaged.

There are many tools to repair registry. One is built-in in Windows (scanreg.exe).


scanreg /fix

You need administrator rights.

If this wont help - look at duDE answer (about tool from SysInternals).

You may also run some filesystem check and see loogs in event viewer to find out what caused your problem.

Where HKEY_CURRENT_USER data is stored in Windows?

From Wikipedia (Windows Registry article):

The HKEY_CURRENT_USER key is a link to the subkey of HKEY_USERS that corresponds to the user; the same information is accessible in both locations. On Windows NT systems, each user's settings are stored in their own files called NTUSER.DAT and USRCLASS.DAT inside their own Documents and Settings subfolder (or their own Users sub folder in Windows Vista and above). Settings in this hive follow users with a roaming profile from machine to machine.

(Documents and Settings was renamed to Users in Windows Vista and later)

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