Windows .exe file association broken - every program (incl cmd, regedit, notepad, taskmgr) launches Excel - Not a dup

THIS IS NOT A DUPLICATE - I HAVE TRIED THE EXISTING REMEDY

I have already read all the SU posts on repairing a broken .EXE file association, and also read the Microsoft article.

All of these make the assumption that you can still launch certain programs, like cmd.exe, Notepad, Regedit or taskmgr. On my system I cannot launch ANY .exe directly (some file associations still work), they all launch Excel and attempt to open the .exe file in Excel.

This all started when I added a file association for .tsv (tab-separated values) pointing to Excel. Every icon for an executable in my taskbar or desktop changed to the Excel icon.

In my case I (thought I) was lucky because I had an open text editor and was able to create the .reg file described in the Microsoft article.

The .reg file merged without errors. However, after rebooting what I saw was an open Excel with many, many popups including messages like

The file format and extension of 'SystemPropertiesProtection.exe' don't match.
The file could be corrupted or unsafe. Unless you trust its source, don't open it.

Or

Microsoft Office has identified a potential security concern.
Warning: The digital signature is valid but the signature is from a publisher whom you have not yet chosen to trust
File Path: C:\Program Files\TechSmith\Snagit 2021\SnagitEditor.exe

Essentially one popup for every startup program.

Now when I attempt to execute ANY program (with a couple of exceptions, below) I get the same behavior -- Excel launches and complains about the input file.

There are a few exceptions:

• I cannot run Firefox directly. However, I run the Ubiquiti Unifi controller for my Wifi LAN. That program did start, and it has a button to open the Wifi dashboard in a browser. Clicking on that button started Firefox correctly.

• My background 1Password app started at boot.

• Sysinternals Process Explorer started at boot.

• It seems a few file associations do not depend on the .exe association to launch their programs.

  • .txt -> TextPad
  • .pdf -> Acrobat Reader

Process Explorer has a File/Run... option, but attempting to use it to launch anything just launches Excel.

Attempting to launch Taskmgr.exe via Ctrl-Shift-ESC, or Ctrl+Alt+Del and selecting Task Manager just launches Excel.

UPDATE: I booted into the recovery command line and examined the registry hive for my user. The key given in the Microsoft document (FileExts) does not exist. The CLASSES registry tree entry for .exe doesn't look unusual. It appears file associations may no longer be stored in the registry.

Question: Is there any user-accessible way to launch a program in Windows 10 that executes the program directly instead of going through file associations? Can anyone suggest how to open regedit.exe without going through file associations?

Solution 1:

I was able to resolve this.

The key was that I could open any program, but only via a file association, not directly. So I finally realized I could create a .bat file containing start cmd.exe and launch THAT (as Administrator) from its desktop icon, giving me an elevated command prompt.

From there I could launch regedit, and what I found clearly hints at a huge bug in association management.

I created the .tsv->Excel association yesterday, as I was dealing with a bunch of tab-separated-value files. I used the "Open With" context menu item from a .tsv file on the desktop and chose Excel from the list of candidates.

When I did that, windows created registry keys:

[HKEY_CLASSES_ROOT\.tsv_auto_file]
[HKEY_CLASSES_ROOT\.tsv_auto_file\shell]
[HKEY_CLASSES_ROOT\.tsv_auto_file\shell\open]
[HKEY_CLASSES_ROOT\.tsv_auto_file\shell\open\command]
@="\"C:\\Program Files\\Microsoft Office\\root\\Office16\\EXCEL.EXE\" \"%1\""

[HKEY_CLASSES_ROOT\.tsv]
@=".tsv_auto_file"
"PerceivedType"="text"

That looks normal. But for some unknown reason, it also changed the association for .exe

[HKEY_CLASSES_ROOT\.exe]
@=".tsv_auto_file"
"ContentType"="application/x-msdownload"

Huh??????

This was easy to fix by searching for .exe associations that had a default value of ".tsv_auto_file" and changing them back to "exefile". In my particular instance the keys I had to reset were

[HKEY_CLASSES_ROOT\.exe]
@="exefile"
[HKEY_CURRENT_USER\Software\Classes\.exe]
@="exefile"
[HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\FileExts\.exe\OpenWithProgids]
"exefile"=hex:

I also deleted the .tsv/.tsv_auto_file association for good measure as I no longer need it. After rebooting, my system is back to behaving normally.

Solution 2:

OK, if you can creaete & merge .reg files, do so with the following:

Windows Registry Editor Version 5.00

[HKEY_CLASSES_ROOT\*\shell\Launch\Command]
@="\"%1\""

Then navigate to 'C:\Windwows\Regedit.exe" ( via a TextPad dialog if you can't open an Explorer window ), right-click & select Launch.

If that's successful, first check this key:

HKCU\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\FileExts\.exe

If a subkey named UserChoice exists, delete it. Then check the associations under HKCR:

Windows Registry Editor Version 5.00

[HKEY_CLASSES_ROOT\.exe]
@="exefile"
"Content Type"="application/x-msdownload"

[HKEY_CLASSES_ROOT\.exe\PersistentHandler]
@="{098f2470-bae0-11cd-b579-08002b30bfeb}"

[HKEY_CLASSES_ROOT\exefile]
@="Application"
"EditFlags"=hex:38,07,00,00
"FriendlyTypeName"=hex(2):40,00,25,00,53,00,79,00,73,00,74,00,65,00,6d,00,52,\
  00,6f,00,6f,00,74,00,25,00,5c,00,53,00,79,00,73,00,74,00,65,00,6d,00,33,00,\
  32,00,5c,00,73,00,68,00,65,00,6c,00,6c,00,33,00,32,00,2e,00,64,00,6c,00,6c,\
  00,2c,00,2d,00,31,00,30,00,31,00,35,00,36,00,00,00

[HKEY_CLASSES_ROOT\exefile\DefaultIcon]
@="%1"

[HKEY_CLASSES_ROOT\exefile\shell]

[HKEY_CLASSES_ROOT\exefile\shell\open]
"EditFlags"=hex:00,00,00,00

[HKEY_CLASSES_ROOT\exefile\shell\open\command]
@="\"%1\" %*"
"IsolatedCommand"="\"%1\" %*"

[HKEY_CLASSES_ROOT\exefile\shell\runas]
"HasLUAShield"=""

[HKEY_CLASSES_ROOT\exefile\shell\runas\command]
@="\"%1\" %*"
"IsolatedCommand"="\"%1\" %*"

[HKEY_CLASSES_ROOT\exefile\shell\runasuser]
@="@shell32.dll,-50944"
"Extended"=""
"SuppressionPolicyEx"="{F211AA05-D4DF-4370-A2A0-9F19C09756A7}"

[HKEY_CLASSES_ROOT\exefile\shell\runasuser\command]
"DelegateExecute"="{ea72d00e-4960-42fa-ba92-7792a7944c1d}"

[HKEY_CLASSES_ROOT\exefile\shellex]

[HKEY_CLASSES_ROOT\exefile\shellex\ContextMenuHandlers]
@="Compatibility"

[HKEY_CLASSES_ROOT\exefile\shellex\ContextMenuHandlers\Compatibility]
@="{1d27f844-3a1f-4410-85ac-14651078412d}"

[HKEY_CLASSES_ROOT\exefile\shellex\ContextMenuHandlers\PintoStartScreen]
@="{470C0EBD-5D73-4d58-9CED-E91E22E23282}"

[HKEY_CLASSES_ROOT\exefile\shellex\DropHandler]
@="{86C86720-42A0-1069-A2E8-08002B30309D}"

[HKEY_CLASSES_ROOT\exefile\shellex\PropertySheetHandlers]

[HKEY_CLASSES_ROOT\exefile\shellex\PropertySheetHandlers\ShimLayer Property Page]
@="{513D916F-2A8E-4F51-AEAB-0CBC76FB1AF8}"