Can you automate changing default application for a file type?

dalchina said:

What's your Windows build? (Win key + r, winver). (Sadly still not a forum requirement).


Try restarting... and if it changes, try disabling fast startup if enabled and repeat the process.

Build is 17134.706. I tried rebooting but the setting didn't change.

dalchina said:

Current build 1803. Interesting it's not consistent. I suggest there's a trigger there somewhere that's causing it to flip.. see if you can identify it. Make sure you have a pdf file icon visible as much as possible, and try to note when it changes indicating the association has changed.

I'll keep an eye out, but if the trigger isn't on either of the obvious occasions — system startup and starting the app — then it may be very difficult to spot. This brings me back to my original question: As a workaround, could I write a shell script to change the default handler for pdf and run that on a schedule?

After doing a bit or research, it seems that I ought to be able to do something using the assoc and ftype commands in a cmd shell, but I can't seem to get them to work.

Hello ricecrispies, I'm having the exact same problem with Windows 7 and Sumatra PDF (it changes the default from Sumatra PDF to WPS), so I don't think the version of Windows has anything to do with this problem. I'm also sick of WPS putting up ads in the bottom right of my screen. Excellent program, however it also has some painful features. Might be another lot of Chinese spyware like suggested with their drones

I'm here because I also have the problem of WPS resetting my PDF default from Adobe to WPS.
The PDF box is also unchecked in the WPS Configuration Tools box, yet it keeps resetting, requiring me to go back and open the file with "Choose another app" and then checking the box to make Adobe Acrobat Reader the default.

A few tests reveal that all is not what it seems! My default pdf reader is Sumatra, and that is what is shown in Registry Editor under .pdf, but that is not necessarily the program that will run. I found no association with the .pdf extension using ASSOC under an admin prompt, but could I set one - but that did not seem to change the program that ran when I either dbl-clicked on a pdf in Explorer, or typed the name at the command prompt. Nor did it alter the registry setting.

I could change the association using 'open with' under explorer, and this did change the default (and the icon), but had no effect on either the registry entry or the ASSOC result. Nor did editing the registry.

So it seems (in my case, at least: W10 1903) that neither a command-line ASSOC change nor a registry change (via merge or direct edit) will do the job.