CGMANI-7825 avatar image
2 Votes"
CGMANI-7825 asked erice-3845 published

How is that Google Chrome can make itself the default PDF viewer?

Ok, first of all I DON'T WANT suggestions on how to change my default applications, I'm a very seasoned system administrator and I'm well aware of how to do it.

Since Windows 10 ONLY allows me as a sys admin to set a list of default application associations via an .xml file ONE TIME at a computer login or a user login via GPO, HOW IN THE WORLD DOES GOOGLE CHROME REPEATEDLY KEEP CHANGING THE DEFAULT PDF VIEWER TO ITSELF FOR MY USERS????

I've been working on this for months now and it is really piss poor that Microsoft does not let sys admins control the default file associations to the degree they are doing it now. That would be FAR MORE SECURE than MS deciding that their stupid piss poor browser is the best options if a registry key that controls it is changed. These types of controls might be fine for stupid home users, but not for business. If MS can't successfully allow for optimal functionality between both then perhaps they need to have two lines of products one for business where sys admins are allowed to do their jobs and one for stupid home users.

I just had another user with this issue today. They logged on to their computer, my GPO did its job set the default pdf viewer to Adobe Reader, the user opened/closed several pdf files no problem. A short time later goes to open a pdf file and it opens in CHROME!!!

I scrubbed through the registry on the computer and NOWHERE was there an association between chrome and pdf files, in fact it was quite the opposite every pdf file association and userchoice key was set to Adobe as it should be. However in settings, apps, default apps, view apps by file types it listed chrome and all shortcuts to pdfs had a chrome icon and opened in chrome.

So obviously there is a serious FLAW in Microcraps plan to protect and keep a users default application file associations. So if anyone out there knows how chrome is doing this, when I can't even get around it as a sys admin, or can help fix the root cause of this issue, I would greatly appreciate it.

Thanks in advance!

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LimitlessTechnology-2700 avatar image
0 Votes"
LimitlessTechnology-2700 answered CGMANI-7825 commented

Hello @CGMANI-7825,

I understand all right. In my case took some months (it was an educational entity, with hundreds of PCs) but I hope this can serve as some example:

What the team found was a legacy GPO was used to set either Adobe Read or Adobe Pro as the default PDF reader for the user based on security groups using the next registry key: HKCU\Software\Microsoft\Windows\CurrentVersion\Explorer\FileExts.pdf\UserChoice\Progid. A new Hash value in Windows 10 is also added to UserChoice key.

In a repro we found that either having no ProdID or a randomized ProdID, then opening a PDF with Chrome, Chrome would then be the default PDF application. Basically your file association ProdID MUST match the Adobe version hash. If not it will revert.

Setting the file association to Adobe would then create the correct Hash value, then when accessing a PDF with Chrome, it would reload the default. Then we disabled the GP applying the registry change, and have changed to using the Win10 supported method using Set a default associations configuration file GP for our users.

We did also try with some policy with WMI filtering and as far I remember there was some success in some deployments. I don't have exactly recorded the change documentation, but the related classes:

Application Name: Adobe Acrobat 2017
ProgID: Acrobat.Document.2017
WMI Filter: select from cim_datafile where (Name = "C:\\Program Files (x86)\\Adobe\\Acrobat 2017\\Acrobat\\Acrobat.exe" or Name = "C:\\Program )

Application Name: Adobe Acrobat Reader DC
ProgID: AcroExch.Document.DC
WMI Filter: select * from cim_datafile where (Name = "C:\\Program Files (x86)\\Adobe\\Acrobat Reader DC\\Reader\\AcroRd32.exe" or Name = "C:\\Program Files\\Adobe\\Acrobat Reader DC\\Reader\\AcroRd32.exe")

Application Name: Adobe Acrobat DC
ProgID: Acrobat.Document.DC
WMI Filter: select * from cim_datafile where (Name = "C:\\Program Files\\Acrobat\\acrobat.exe" or Name = "C:\\Program Files (x86)\\Acrobat\\acrobat.exe")

Application Name: Adobe Acrobat X
ProgID: AcroExch.Document
WMI Filter: select * from cim_datafile where (Name = "c:\\Program Files\\Adobe\\Acrobat 10.0\\Acrobat\\Acrobat.exe" or Name = "c:\\Program Files (x86)\\Adobe\\Acrobat 10.0\\Acrobat\\Acrobat.exe")

Application Name: Adobe Acrobat XI
ProgID: Acrobat.Document.11
WMI Filter: select * from cim_datafile where (Name = "C:\\Program Files\\Adobe\\Acrobat 11.0\\Acrobat\\Acrobat.exe" or Name = "C:\\Program Files (x86)\\Adobe\\Acrobat 11.0\\Acrobat\\Acrobat.exe")

Hope this helps with your issue,

--If the reply is helpful, please Upvote and Accept as answer--

· 1
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Thanks for the information. This sounds promising. I'll dig into a bit and post back if I find anything to line up in my environment.

0 Votes 0 ·
Andrew-4723 avatar image
0 Votes"
Andrew-4723 answered ADIT-8728 commented


This issue just came up for me today out of the blue. Everything was fine before with Adobe being the default PDF viewer, and then suddenly all my PDF files have the Chrome icon beside it. In my Outlook, all PDF attachments that people sent me also show the Chrome icon.

I checked and Adobe is set as my default app to open PDF files, so I was really confused.

I am NOT an IT person but I googled to find various possible fixes and I tried a couple with no success. The conversation here is way over my head but since I'm desperate to restore "order", I kept reading. Anyway, I found a simple fix and it actually worked. I forget who to credit but I found it somewhere online, so thanks to that person.

Basically, I went to a file on my computer (which has the Chrome icon beside it). I right-clicked on it and selected "Open with". At this point, I was thinking, "Yeah, yeah, I tried this already". But I read this particular instruction more closely from the webpage I was on, and it said to select "Choose another app". I did that, and Adobe was already selected. BUT THE KEY TRICK IS TO CHECK OFF: "Always use this app to open .pdf files".

I thought, "Can it be this simple?" I tried something like this already but not this actual last step, and sure enough, normalcy was restored! All my PDF files are now showing the Adobe icon beside it, along with the attachments in my Outlook inbox that are supposed to show Adobe.

Because I had trouble finding this simple fix, I thought I would mention what worked for me here, to help my fellow internet users who may be pulling their hair out.

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Thank you Andrew. Followed your lead and what was once baffling turned out to be a simple fix. Thanks so much for sharing this.

0 Votes 0 ·

Thank you so much, Andrew! That fixed my issue. It was really annoying!

0 Votes 0 ·


We are aware of this, and it is our current best option for resolving the issue. However, it has not been a 100% solution. We have had several dozen repeat issues after doing this method, So we are still looking for the silver bullet on this one. What I'm really trying to understand though is how Chrome is able to insert itself as the default pdf viewer in the first place. Supposedly Microcrap has put measures in place to only allow the user to select the default apps, and us as admins can set them only ONCE at initial login, and if it is done any other way Microcrap will revert it to their crappy browser as the default pdf viewer. However in this case they are not able to do it for some reason, Chrome inserts itself and Microcrap leaves it alone, Why?????? How?????? Oh, yeah, it is a Microcrap solution!!!

0 Votes 0 ·

The "Set as Default" is not the solution unfortunately.


I'm seeing the same thing with a single user. I have no PDF GPO's setup in the domain.

I've narrowed this down to when the user Uploads a PDF thru a website in Chrome. Chrome then assumes control. I don't know if MS Edge does the same thing (I'll have her test it on her next upload).

Check to see if you user is doing the same thing.

0 Votes 0 ·
erice-3845 avatar image
0 Votes"
erice-3845 answered erice-3845 published

IT admin here. In the last few weeks, I've had this issue spreading across my entire ecosystem. I've been setting the default app associations via the local GPO for years to point to an XML file stored on a share on my file server, and have had zero issues. Now, out of the blue, Chrome is taking over user PC's slowly but surely. The fix, weirdly enough, has been to disable the GPO. That's not a long-term solution however, as I want Chrome to be the forced default browser, and Microsoft seems to love pushing Edge out as the default when doing Win10 version updates.

All PC's are running Reader DC

Here's my XML file, stored on a hidden share of the file server, permissions set for it to be Read-Only by everyone company wide:

<?xml version="1.0" encoding="UTF-8"?>
<Association Identifier=".3g2" ProgId="VLC.3g2" ApplicationName="VLC media player" />
<Association Identifier=".3gp" ProgId="VLC.3gp" ApplicationName="VLC media player" />
<Association Identifier=".3gp2" ProgId="VLC.3gp2" ApplicationName="VLC media player" />
<Association Identifier=".3gpp" ProgId="VLC.3gpp" ApplicationName="VLC media player" />
<Association Identifier=".aac" ProgId="VLC.aac" ApplicationName="VLC media player" />
<Association Identifier=".acrobatsecuritysettings" ProgId="Applications\AcroRd32.exe" ApplicationName="Adobe Acrobat Reader DC" />
<Association Identifier=".adts" ProgId="VLC.adts" ApplicationName="VLC media player" />
<Association Identifier=".aif" ProgId="VLC.aif" ApplicationName="VLC media player" />
<Association Identifier=".aifc" ProgId="VLC.aifc" ApplicationName="VLC media player" />
<Association Identifier=".aiff" ProgId="VLC.aiff" ApplicationName="VLC media player" />
<Association Identifier=".amr" ProgId="VLC.amr" ApplicationName="VLC media player" />
<Association Identifier=".arw" ProgId="AppX43hnxtbyyps62jhe9sqpdzxn1790zetc" ApplicationName="Photos" />
<Association Identifier=".asf" ProgId="VLC.asf" ApplicationName="VLC media player" />
<Association Identifier=".asx" ProgId="VLC.asx" ApplicationName="VLC media player" />
<Association Identifier=".au" ProgId="" ApplicationName="VLC media player" />
<Association Identifier=".avi" ProgId="VLC.avi" ApplicationName="VLC media player" />
<Association Identifier=".bmp" ProgId="AppX43hnxtbyyps62jhe9sqpdzxn1790zetc" ApplicationName="Photos" />
<Association Identifier=".cda" ProgId="VLC.cda" ApplicationName="VLC media player" />
<Association Identifier=".cr2" ProgId="AppX43hnxtbyyps62jhe9sqpdzxn1790zetc" ApplicationName="Photos" />
<Association Identifier=".crw" ProgId="AppX43hnxtbyyps62jhe9sqpdzxn1790zetc" ApplicationName="Photos" />
<Association Identifier=".dib" ProgId="AppX43hnxtbyyps62jhe9sqpdzxn1790zetc" ApplicationName="Photos" />
<Association Identifier=".erf" ProgId="AppX43hnxtbyyps62jhe9sqpdzxn1790zetc" ApplicationName="Photos" />
<Association Identifier=".flac" ProgId="VLC.flac" ApplicationName="VLC media player" />
<Association Identifier=".gif" ProgId="AppX43hnxtbyyps62jhe9sqpdzxn1790zetc" ApplicationName="Photos" />
<Association Identifier=".htm" ProgId="ChromeHTML" ApplicationName="Google Chrome" />
<Association Identifier=".html" ProgId="ChromeHTML" ApplicationName="Google Chrome" />
<Association Identifier=".inf" ProgId="inffile" ApplicationName="Notepad" />
<Association Identifier=".ini" ProgId="inifile" ApplicationName="Notepad" />
<Association Identifier=".jfif" ProgId="AppX43hnxtbyyps62jhe9sqpdzxn1790zetc" ApplicationName="Photos" />
<Association Identifier=".jpe" ProgId="AppX43hnxtbyyps62jhe9sqpdzxn1790zetc" ApplicationName="Photos" />
<Association Identifier=".jpeg" ProgId="AppX43hnxtbyyps62jhe9sqpdzxn1790zetc" ApplicationName="Photos" />
<Association Identifier=".jpg" ProgId="AppX43hnxtbyyps62jhe9sqpdzxn1790zetc" ApplicationName="Photos" />
<Association Identifier=".jxr" ProgId="AppX43hnxtbyyps62jhe9sqpdzxn1790zetc" ApplicationName="Photos" />
<Association Identifier=".kdc" ProgId="AppX43hnxtbyyps62jhe9sqpdzxn1790zetc" ApplicationName="Photos" />
<Association Identifier=".log" ProgId="txtfile" ApplicationName="Notepad" />
<Association Identifier=".m1v" ProgId="VLC.m1v" ApplicationName="VLC media player" />
<Association Identifier=".m2t" ProgId="VLC.m2t" ApplicationName="VLC media player" />
<Association Identifier=".m2ts" ProgId="VLC.m2ts" ApplicationName="VLC media player" />
<Association Identifier=".m3u" ProgId="VLC.m3u" ApplicationName="VLC media player" />
<Association Identifier=".m4a" ProgId="VLC.m4a" ApplicationName="VLC media player" />
<Association Identifier=".m4p" ProgId="VLC.m4p" ApplicationName="VLC media player" />
<Association Identifier=".m4v" ProgId="VLC.m4v" ApplicationName="VLC media player" />
<Association Identifier=".mid" ProgId="VLC.mid" ApplicationName="VLC media player" />
<Association Identifier=".mka" ProgId="VLC.mka" ApplicationName="VLC media player" />
<Association Identifier=".mkv" ProgId="VLC.mkv" ApplicationName="VLC media player" />
<Association Identifier=".mov" ProgId="" ApplicationName="VLC media player" />
<Association Identifier=".MP2" ProgId="VLC.mp2" ApplicationName="VLC media player" />
<Association Identifier=".mp2v" ProgId="VLC.mp2v" ApplicationName="VLC media player" />
<Association Identifier=".mp3" ProgId="VLC.mp3" ApplicationName="VLC media player" />
<Association Identifier=".mp4" ProgId="VLC.mp4" ApplicationName="VLC media player" />
<Association Identifier=".mp4v" ProgId="VLC.mp4v" ApplicationName="VLC media player" />
<Association Identifier=".mpa" ProgId="VLC.mpa" ApplicationName="VLC media player" />
<Association Identifier=".MPE" ProgId="VLC.mpe" ApplicationName="VLC media player" />
<Association Identifier=".mpeg" ProgId="VLC.mpeg" ApplicationName="VLC media player" />
<Association Identifier=".mpg" ProgId="VLC.mpg" ApplicationName="VLC media player" />
<Association Identifier=".mpv2" ProgId="VLC.mpv2" ApplicationName="VLC media player" />
<Association Identifier=".mrw" ProgId="AppX43hnxtbyyps62jhe9sqpdzxn1790zetc" ApplicationName="Photos" />
<Association Identifier=".mts" ProgId="VLC.mts" ApplicationName="VLC media player" />
<Association Identifier=".nef" ProgId="AppX43hnxtbyyps62jhe9sqpdzxn1790zetc" ApplicationName="Photos" />
<Association Identifier=".nrw" ProgId="AppX43hnxtbyyps62jhe9sqpdzxn1790zetc" ApplicationName="Photos" />
<Association Identifier=".orf" ProgId="AppX43hnxtbyyps62jhe9sqpdzxn1790zetc" ApplicationName="Photos" />
<Association Identifier=".pdf" ProgId="AcroExch.Document.DC" ApplicationName="Adobe Acrobat Reader DC" />
<Association Identifier=".pdfxml" ProgId="Applications\AcroRd32.exe" ApplicationName="Adobe Acrobat Reader DC" />
<Association Identifier=".pef" ProgId="AppX43hnxtbyyps62jhe9sqpdzxn1790zetc" ApplicationName="Photos" />
<Association Identifier=".png" ProgId="AppX43hnxtbyyps62jhe9sqpdzxn1790zetc" ApplicationName="Photos" />
<Association Identifier=".ps1" ProgId="Microsoft.PowerShellScript.1" ApplicationName="Notepad" />
<Association Identifier=".psd1" ProgId="Microsoft.PowerShellData.1" ApplicationName="Notepad" />
<Association Identifier=".psm1" ProgId="Microsoft.PowerShellModule.1" ApplicationName="Notepad" />
<Association Identifier=".ra" ProgId="VLC.ra" ApplicationName="VLC media player" />
<Association Identifier=".raf" ProgId="AppX43hnxtbyyps62jhe9sqpdzxn1790zetc" ApplicationName="Photos" />
<Association Identifier=".ram" ProgId="VLC.ram" ApplicationName="VLC media player" />
<Association Identifier=".raw" ProgId="AppX43hnxtbyyps62jhe9sqpdzxn1790zetc" ApplicationName="Photos" />
<Association Identifier=".rmi" ProgId="VLC.rmi" ApplicationName="VLC media player" />
<Association Identifier=".rw2" ProgId="AppX43hnxtbyyps62jhe9sqpdzxn1790zetc" ApplicationName="Photos" />
<Association Identifier=".rwl" ProgId="AppX43hnxtbyyps62jhe9sqpdzxn1790zetc" ApplicationName="Photos" />
<Association Identifier=".s3m" ProgId="VLC.s3m" ApplicationName="VLC media player" />
<Association Identifier=".scp" ProgId="txtfile" ApplicationName="Notepad" />
<Association Identifier=".snd" ProgId="VLC.snd" ApplicationName="VLC media player" />
<Association Identifier=".sr2" ProgId="AppX43hnxtbyyps62jhe9sqpdzxn1790zetc" ApplicationName="Photos" />
<Association Identifier=".srw" ProgId="AppX43hnxtbyyps62jhe9sqpdzxn1790zetc" ApplicationName="Photos" />
<Association Identifier=".tif" ProgId="PhotoViewer.FileAssoc.Tiff" ApplicationName="Windows Photo Viewer" />
<Association Identifier=".tiff" ProgId="PhotoViewer.FileAssoc.Tiff" ApplicationName="Windows Photo Viewer" />
<Association Identifier=".TS" ProgId="VLC.ts" ApplicationName="VLC media player" />
<Association Identifier=".TTS" ProgId="VLC.tts" ApplicationName="VLC media player" />
<Association Identifier=".txt" ProgId="txtfile" ApplicationName="Notepad" />
<Association Identifier=".url" ProgId="IE.AssocFile.URL" ApplicationName="Internet Browser" />
<Association Identifier=".vlt" ProgId="VLC.vlt" ApplicationName="VLC media player" />
<Association Identifier=".voc" ProgId="VLC.voc" ApplicationName="VLC media player" />
<Association Identifier=".wav" ProgId="VLC.wav" ApplicationName="VLC media player" />
<Association Identifier=".wdp" ProgId="AppX43hnxtbyyps62jhe9sqpdzxn1790zetc" ApplicationName="Photos" />
<Association Identifier=".website" ProgId="IE.AssocFile.WEBSITE" ApplicationName="Internet Explorer" />
<Association Identifier=".wma" ProgId="VLC.wma" ApplicationName="VLC media player" />
<Association Identifier=".wmv" ProgId="VLC.wmv" ApplicationName="VLC media player" />
<Association Identifier=".WPL" ProgId="VLC.wpl" ApplicationName="VLC media player" />
<Association Identifier=".wsz" ProgId="VLC.wsz" ApplicationName="VLC media player" />
<Association Identifier=".wtx" ProgId="txtfile" ApplicationName="Notepad" />
<Association Identifier=".wvx" ProgId="VLC.wvx" ApplicationName="VLC media player" />
<Association Identifier=".xht" ProgId="xhtmlfile" ApplicationName="Internet Explorer" />
<Association Identifier=".xhtml" ProgId="xhtmlfile" ApplicationName="Internet Explorer" />
<Association Identifier=".xm" ProgId="VLC.xm" ApplicationName="VLC media player" />
<Association Identifier=".zpl" ProgId="VLC.zpl" ApplicationName="VLC media player" />
<Association Identifier="bingmaps" ProgId="AppXp9gkwccvk6fa6yyfq3tmsk8ws2nprk1p" ApplicationName="Maps" />
<Association Identifier="http" ProgId="ChromeHTML" ApplicationName="Google Chrome" />
<Association Identifier="https" ProgId="ChromeHTML" ApplicationName="Google Chrome" />
<Association Identifier="microsoft-edge" ProgId="AppX7rm9drdg8sk7vqndwj3sdjw11x96jc0y" ApplicationName="Microsoft Edge" />
<Association Identifier="microsoft-edge-holographic" ProgId="AppX3xxs313wwkfjhythsb8q46xdsq8d2cvv" ApplicationName="Microsoft Edge" />
<Association Identifier="ms-xbl-3d8b930f" ProgId="AppXdn5b0j699ka5fqvrr3pgjad0evqarm6d" ApplicationName="Microsoft Edge" />

The ProgID looks correct, and I've been smacking my head around for weeks on this. I'll take any insight at this point.

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