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Whenever I want to create a new text file using Windows 7 Explorer’s New ⇨ Text File context-menu entry, I get a file with an uppercase extension. For example instead of New Text Document.txt, I get New Text Document.TXT.

I searched HKEY_CLASSES_ROOT and found a key named .TXT. I renamed it to .txt and after rebooting, it works as expected. Unfortunately, after a while, it started happening again.

Synetech
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Torsten
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    You may use regmon or procmon tool from SysInternals family to find out which process is modifying this registry key, this will give you some clues to the reason of the problem. – Jack Shainsky May 05 '11 at 09:30
  • @Jack Shainsky Thanks. How do I use it? I set up a filter like this: Path contains HKEY_CLASSES_ROOT then Include. Will this be sufficient? – Torsten May 06 '11 at 12:54
  • regmon uses a shortcut for HKEY_CLASSES_ROOT, so you should set the filter for HKCR. I would set it for HKCR\.txt for getting only the messages that you're interested in. – Jack Shainsky May 08 '11 at 10:28
  • I have this as well, do you happen to use Notepad++? – Brave Newbie Feb 02 '12 at 19:10
  • @Qosmo No, I don't have it installed and I think I didn't install it ever on the machine I'm having trouble with. – Torsten Feb 08 '12 at 12:29
  • You indicated that the problem returns after a while. Do you mean that `HKCR\.txt` gets changed back to `HKCR\.TXT` or *just* the symptom (i.e., it is still `\.txt`, but new files have uppercase extensions)? Did you try monitor register writes? – Synetech Dec 02 '12 at 05:34
  • @Synetech It's been a while, but I think it was just the symptom. – Torsten Nov 21 '19 at 08:46

1 Answers1

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Try the following:

  • Open the registry editor (Start ⇨ regedit)
  • Navigate to the key HKEY_CLASSES_ROOT\.TXT
  • Select File ⇨ Export and save it to a .reg file
  • Open the .reg file in a text-editor (e.g., Notepad)
  • Perform a search-and-replace to replace all instances of .TXT to .txt
  • Save
  • In regedit, delete the key HKEY_CLASSES_ROOT\.TXT
  • Double-click the .reg file and select [Yes] to import/merge it
  • Reboot
Synetech
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user177401
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