Forum moved here!

Home / Registering Sumatra as the Default PDF Reader in Windows 10


Thank you, administrator (and robot, of course, LOL), for admitting me to this forum. I’ll try to contribute with my knowledge whenever I know something as a fact or factual experience. However, I’m not systems savvy. Since Windows 10, with its new graphic user interface, I’m actually lost due to the “glitz and glamour” of the W10 tiles and new windows format which seems to me to be an attempt to imitate Android.

The program is very nice. It loads quickly and also displays quickly many PD files in one window. I have been using it for many years without difficulties on XP and W7 computers.

It also works on W10, but I don’t know how to make it the default program so that it starts up whenever I click on a PD file in Windows Explorer. I knew how to configure this on W7 starting at its Control Panel window.

I tried the same in W10, but the Control Panel “kicks” me into this new tile interface and windows display format. Sumatra is not listed in said windows as an option, neither does PDF appear.

Sumatra was installed directly through the FireFox browser as a 64-bit program on a Spanish language w10. Whenever I click on the Sumatra icon, it starts up and asks me in a small window whether I would like it to be my default reader. Of course, I do, but it does not register.

I hope that someone knows where and how I am going wrong.



welcome, you are not doing anything “wrong” it is Windows 10 constantly trying to redirect the default PDF reader to EDGE
I do not know Spanish language W10 the first place to try in English is “default app”

The installer still allows for Win XP / 7 / 8 /8.1 users to confirm they want SumatraPDF to be the PDF and other document types default reader.

Microsoft in the name of security have intentionally blocked traditional methods installers use for deciding what app is to be default PDF handler in Windows 10. Adobe Acrobat has clearly changed its approach to alter that security restriction, hence you may see later comments to install and uninstall Acrobat, I do not recommend that as the solution.

Unless you are a Professional Administrator using GPE or DISM to roll out to multiple users using pairs of appassoc.xml then Ignore trying to set associations by any other means than as explained in


Thank you, it worked. Ingenious! I followed your instructions, looking up some words in the dictionary.

These are the steps in Spanish:
All the windows that pop up have a black, not white, background

  1. In the search box (of the looking glass): Aplicaciones predeterminadas
  2. An empty window pops up and after 10 seconds or so it fills up, similar to the first photo.
    Click on “Eligir aplicaciones predeterminadas por tipo de archivo”
  3. A similar, but different, empty window pops up which takes some time to fill, similar to the second photo above.
    With the “AvPág” (Page Down) key scroll to “.pdf”, just like above.
  4. Click on “Microsoft Edge” and a small (black) window pops up.
  5. Select SumatraPDF
  6. Leave the window
    It works, hurray!!!

The example helped me find my way through the “glitz and glamour” of W10 windows, especially those with a black background on a black desktop. It is difficult to see the boundaries. Also, I observed that text is often written in grey instead of black which makes it difficult to read.
I am wondering whether you too found the W10 style more difficult than W7, or whether is it just me since I am “tuned” to text and schematics, expecting clear boundaries.


Thanks for your explanation which may help other Spanish users

Your comments about colour suggest your app theme is set to dark rather than light

have you changed color settings ?


Yes, I did, and now I can see the three window’s icons on the top right.
In the image above, the right frame agreed with the one my computer shows, but the left frame had a different layout. Just to show that not every configuration must be the same.
Thanks for your help.


It’s not a config issue. Blame Microsoft for it. Windows 10 is a constant Work in Progress, and as such every iteration (minor or major update/upgrade) has the potential to change the UI and functionality.


We have set Sumatra PDF as default application over the xml file.

Is it possible to disable the question at the first start (Make Sumatra PDF default application for PDF Files? Don’t ask me again).


This question usually arises with windows 10 non-admin users, but if your using DISM I have to presume you are an admin and have enabled users OS rights etc, In which case there are a few suggestions.

There are 3 methods listed here
I had no problems on Windows prior to 10 as an admin user in selecting make as default in the SumatraPDF menu > settings > options, UNLESS I FORGOT to check Don’t ask me again

In Windows 10 that request seems to be OVERRIDDEN as EDGE protection instantly redirects it back ! which I suspect is what your are having problems with.

So you would need to try the second method, however that does not always cut it so you could jump straight to the third
The known way to force edge not to reset pdf handling back to itself (apart from uninstalling 10, which was my first choice on 2 out of 4 pcs) as described at the end of the linked guide above is you need to go to Windows Settings > Default app settings > Choose default applications by file type (NOT Set defaults by app) and change it as shown here


I had the same problem.
My solution:
don’t change directly from Edge -> Sumatra.

  • install Adobe Reader.
  • set Adobe Reader as default app
  • set afterwards Sumatra as default app
    This worked for me.

I installed the add on Open in Pdf

So i’m not dependent of the settings of Windows in the future (as far as my browser is concerned).


With my new installation of windows 10 pro (v 1803) I have the same problem. Your workaround by first enabling Adobe did not work in my case. Also with other filetypes (like cbr) it is not possible for me to set Sumatra as default reader for those types.


DO NOT USE third party add-ons to work around this issue since we will NOT be able to support those problems. most of the issues with various windows updates are exactly that i.e ISSUES with the way windows has changed.
IF you wish to support multiple types of file use the install as administrator ENSURE you use OPTIONS if you want to include pdf preview and set as default handler. Windows may ignore SumatraPDFs request to be default .pdf handler and keep resetting .pdf handler to Edge. SO after install follow these SUPORTED instructions
there is more on how it keeps changing in this bug report and previous


Finally I was able to make Sumatrapdf default pdf reader, but when I tried to do the same for cbr files it did not work.


It should be fairly simple to reset any type such as CBR in a similar fashion
That is using settings > goto choose default applications by file type scroll down to .cbr and if the box is grey with a cross choose a default and if SumatraPDF is listed select it.

IF not listed (ONLY look for app in the store) then you need to go LONGWAYS round
Find a .cbr file, Right click and from the choices select “open with”
that may show SumatraPDF and a tick box for always use this app to open.cbr files,
Make sure box is ticked
IGNORE the icons and click on the MORE apps
go to the bottom and select
LOOK for more apps find SumatraPDF.exe in either your program files or program files (86)
Select SumatraPDF.EXE, that should fix it, If not you would need to do the same but as the administrator

What MAY happen is when you select open by type you see two (or more) SumatraPDF icons and when you try those it does not seem to work in that case it is best to re START as administrator find a file and reinforce the correct sequence following the LONGWAYs above until you click on SumatraPDF.EXE as the new default opener


Some Windows 10 builds (possibly including 1803) may have broken association with default application. In such cases workarounds may not work and you can’t force system to open your file in a proper app when clicking it. You must do it in a traditional way - run a program, then use menu File | Open.


Impossible de mettre Sumatra PDF par défaut pour ouvrir les PDF.
Que faire?

[Moderator added translation: Cannot set Sumatra PDF by default to open PDFs.
What to do?]


@mehdig: Which version and build of Windows are you using? (Check under Settings app > System > About.)

Have you tried the following yet to change the default app for PDFs?


Using Windows 10 64 I’can’t register SumatraPDF 3.2 as the default PDF from command line with


The command functioned well in Win XP 7 & 8
Windows 10 will not allow you to use that method (afaik, but I have not tried to force it recently)
Windows 10 expects Edge to be the Default PDF reader and persuading it to not do so has been a to and fro battle which varies per release

I install on Windows 10 without that option
Then kick windows in the shins by selecting a pdf and telling associations
its my fervent wish it allows SumattraPDf to open similar such files


Windows 10 doesn’t allow programs to do it themselves (unlike earlier versions).

You have to do it as described at


The following also works for me equally well: