How to change .tmp extension back to no app association

Topic

New Reply

Dumb move, but I opened a .tmp file using notepad and forgot to uncheck the “always use this app”.  Now all my .tmp files are assigned to notepad!

How can I remove this association and put .tmp expension back to the unassigned category as it was originally? (So it asks what to Open the file with each time?)

Thx

Windows 11 Pro v24H2 and Windows 10 Pro x64 v22H2

Reply | Quote

Replies

Right-click on a .tmp file. Select ‘open with’, uncheck ‘always…’

Reply | Quote

How to Undo the “Open With” default program association for a file type:

Google Search: “undo default open with”

Try this:

Open regedit

Navigate to HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\FileExts\

Find the entry for the extension needed (e.g. .tmp)

Edit the OpenWithList key and remove any unwanted programs (Fix the MRU list as well)

Check the OpenWithProgids key to be sure it is correct

Make sure there is no subkey/subfolder named UserChoice
(If you see it, right click on the UserChoice and click Delete)

I found that the above worked fine, no restart required.

Reply | Quote

I did this accidental rename of .tmp file but tried your HotKey method, but I don’t know what the correct files in the folders should look like.  You said remove any app/file that is wrong, but there were 2 other files in there, that I did not delete but did all the other tasks.  I still have a .tmp file opening w/app, so it didn’t work.  Appreciate the assistance ~

Reply | Quote

JC Zorkoff wrote:

Check the OpenWithProgids key to be sure it is correct

Make sure there is no subkey/subfolder named UserChoice
(If you see it, right click on the UserChoice and click Delete)

Actually, to restore things so .tmp isn’t assigned to ANY program, you need to delete both the OpenWithProgids and UserChoice keys.

Reply | Quote