Sumatra PDF is a PDF, ePub, MOBI, CHM, XPS, DjVu, CBZ, CBR reader for Windows

Sumatra PDF won't open additional files with double click on PDF files

I am using Sumatra PDF V-3.2 in Windows 10.

It happens frequently that if I have some files open (even just one) in Sumatra PDF, and I click on another PDF file in my file explorer (the standard double click), it doesn’t open, nothing happens. In order to open an additional file, I have to open file explorer from inside Sumatra app (using CTRL+O, which opens the file explorer) and select the files to open.

This doesn’t happen always, but now and then.

This issue wasn’t there before in earlier versions I used. I have been using this software since last 5 years, it worked pretty well before.

Sumatra is my only/default external PDF reader in my PC.

If your on Windows 10 as most users are, then it is not uncommon to have file association problems since MS defauled PDF as a native Edge file, It is still that way on my PC since I cant be bothered to keep reseting it except for some testing. I personally use shortcuts ( that can also fail to work since MS insist each one needs to be controlled) I dont have any of those issues on either Windows 7 systems.

Having said that, once the default is sucessfully set to SumatraPDF, it should always work, unless there is some older historic non working association available that windows in its wisdom, uses by preference.
Since you have updated it seems that windows may be trying to send the pdf to an older registry entry. I hesitate to suggest using a registry cleaner since that has the potential to make matters worse. If you have some knowledge of registry entries it is worth doing a simple search for “SumatraPDF” and see if there are any rogue old .exe entries in old paths that you can correct manually, rather than letting a cleaner loose on all the full range of problems a registry can have. I will occasionally clean out those I find after testing different versions since I dont want windows to attempt to use them over any other version.

Doesn’t sound like an association problem since double-clicking files works at times and fails on other occasions. How are you launching Sumatra? Make sure you’re not running it elevated i.e. as admin, or else double-clicking PDFs in a non-elevated copy of Explorer will result in behavior just as you’ve described.

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having same problem after edge installed. icons are still sumatra, but double-clicking them doesn’t open edge or sumatra. uninstall/reinstall of sumatra doesn’t fix anything; even when told it is the associated program, the icons remain edge. settings for default apps seem to believe sumatra is in charge, but it isn’t unless you open the file from within sumatra.

fyi: i just insisted with “choose default apps by file type”, and i’m fine once again. if anyone knows how to uninstall edge completely, i’d willingly become the guinea pig

When Windows sees change to the link to a pdf file association it will often try to reset it to edge but it does not always ensure it is restored correctly. It will happily try to keep all the old pdf historic associations even if they are no longer correct. thus you may see what looks like a valid old link but behind the scenes it links to a file that’s no longer there.
Assuming you have not changed the filename to not include “sumatra” at a command prompt you can try (beware each search may take some time)

reg query "HKCR\Local Settings\Software\Microsoft\Windows\Shell" /f "*Sumatra*" /s

and

reg query "HKCU\SOFTWARE\Classes\Local Settings\Software\Microsoft\Windows\shell" /f "*Sumatra*" /s

Ideally each should only return ONE same entry pair
but in my system I get 5 old pairs in each case and neither first or last is the default, that is found from

reg query HKCU\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\FileExts\.pdf\UserChoice

that entry stores a hash value and if for whatever legitimate UserChoice reason the hash changes it may not function (damn MS multi-layered security blockers)

A related issue is shortcuts are not always reflected by the registry entries and the start tile can even point to a different location to the one it pinned previously to the taskbar
I find this most common when using the taskbar and context menus when changing between daily builds, so there I have used one common location workaround which is not the same as my default, because the alternative is to remove and replace the links each day I update.
The only way I know for ensuring the association is restored is to first ignore every existing link and do a totally fresh association which involves right click a pdf select “open with” and ignore any SumatraPDF icon keep taking last option until you “Look for another app on this PC” and select the desired current EXE most importantly with “always use” active