9 Replies Latest reply on Oct 18, 2013 7:38 AM by lenainjaune

    AcroRd32.exe Background Scanning in Explorer


      TL;DR: AcroRd32.exe is possibly scanning files in the background, I do not know why.


      Hello. I cannot seem to find this answer anywhere, and thought I'd post here.


      I have installed Adobe Reader X ( and am currently running Win7 32-bit.


      What I have observed is that when I am in Explorer browsing through my files, every now and then I'll notice in my Task Manager a few AcroRd32.exe's running. It happens whenever I open a folder that contains .pdf files. There'll be about 2 instances of AcroRd32.exe running briefly (~2 seconds), then they'll self-terminate.


      Does anybody know what is going on here? It seems to happen only the first time I open a folder. I've even reboot my system, opened up that folder again, and did not find AcroRd32.exe running, so I can confidently say that it is happening only the first time I open a folder.


      To me it seems that AcroRd32 is scanning the folder real quick for something, possibly building a cache database or something. I really don't know what is up, but I'm just curious to know what's going on.


      If you haven't experienced this yet, I suggest keeping task manager open while browsing through folders that contain .pdf files. Again, it seems to only happen the first time you browse through.


      Thank you in advance.

        • 1. Re: AcroRd32.exe Background Scanning in Explorer

          I asked something similar a couple weeks ago and never got a response.

          My problem was that AcroRd32.exe appears when i mouse over a .pdf file on the desktop.

          Are you able to mouse over a pdf on the desktop without it loading?


          1 person found this helpful
          • 2. Re: AcroRd32.exe Background Scanning in Explorer
            BenihanaDarkslide Level 1

            Hey, thanks for posting a response! I was afraid that nobody would notice this issue/feature/whats-it.


            I copied several PDF files to my desktop, and I hovered my mouse over the files but AcroRd32 never started for me. I even clicked on the file, but no AcroRd32. I then rebooted my computer and thought maybe after a fresh restart it may produce your effects, but nope. Still nothing.


            However, I might add, that whenever I copy a PDF (even if it's into the same directory) I get 2 instances of AcroRd32 running temporarily, just like in my original post. So when I copied the files to my desktop, I did get the 2 instances running, but never when mousing over.


            EDIT: Cleaned up grammar.


            Message was edited by: BenihanaDarkslide

            • 3. Re: AcroRd32.exe Background Scanning in Explorer
              ManishPali Adobe Employee

              This is expected behavior, acrord32.exe processes are displayed due to shell extensions. Shell extensions invokes the acrord32.exe process to fetch the PDF related infromation like authot and other data for tooltip, thumbnail and preview etc. More information about shell extensions could be found here http://msdn.microsoft.com/en-us/library/cc144067(v=vs.85).aspx


              Note: Prior to Reader X acrord32info.exe was used for this purpose.

              • 4. Re: AcroRd32.exe Background Scanning in Explorer
                BenihanaDarkslide Level 1

                Mr. Manish, I thank you most sincerely for an exact response.


                I appreciate your statement in bold, as it has answered my follow-up question before my asking.


                You know I never noticed this behaviour prior to Reader X, because I had set DENY permissions on my Acrord32Info.exe (DENY traverse folder/execute file) because it seemed to provide no utility to me at the time.


                So I take it that it is Windows that is invoking Acrord32.exe to gather various details (via. shell extension), and Windows is possibly storing those details somewhere itself. If this is true, then it would explain why I do not see Acrord32.exe running ever again except for the first time. (This would also lead me to ask Seth if you have disabled anything in Windows. Caching, indexing, something around those lines)


                Again, thank you for the answer!

                • 5. Re: AcroRd32.exe Background Scanning in Explorer
                  SethTP Level 1

                  The computer with the issue is Win XP 32bit. I have Indexing and System Restore Disabled.

                  The desktop icons do not show a thumbnail preview, Just the default pdf icon.

                  I thought it was because of Norton AV but disabling had no effect.

                  Im not sure what to try next or what options inside reader to change.

                  • 6. Re: AcroRd32.exe Background Scanning in Explorer
                    Sam878 Level 1

                    Hi All,

                    I'm getting the same behavior (mouseover causes AcroRd32.exe to open; then double-click causes another AcroRd32.exe to open). I've asked a couple of times in the forum, and gotten no response.

                    From above, it says that this is expected behavior -- but this behavior on my poor low-memory machine is causing signficant lag times, and even causes the file to not be opened at all when memory is maxed out and the second instance (to open the PDF) cannot be created.

                    I gather that I would have to disable the Windows "hover" display in order to avoid the problem; which really isn't acceptable.

                    Guess it's time to get rid of Adobe and go to FoxIt Reader or some such software.


                    Thanks for posting this guys. I'll close out my post...

                    • 7. Re: AcroRd32.exe Background Scanning in Explorer
                      nik b.

                      You should be able to get rid of this behavior by invoking the following command:


                      regsvr32 "%CommonProgramFiles%\Adobe\Acrobat\ActiveX\pdfshell.dll" /u


                      Afterwards, reboot your computer. No idea whether this has any undesired side-effects.


                      original information from http://i-tweak.blogspot.com/2009/05/remove-acrord32infoexe.html

                      and http://ralliart12.wordpress.com/2008/03/13/windows-tips-1-modify-acrord32infoexe-to-free-u p-memory/




                      • 8. Re: AcroRd32.exe Background Scanning in Explorer
                        Sam878 Level 1

                        Thanks nik. That worked!

                        There is a side effect. If I try to open Adobe Reader directly (Start/Programs/Adobe Reader X), then the MS installer runs saying that Reader has to be configured. After the configuration, we're back to the undesired behavior again. However, I really don't need to run Adobe Reader directly. I usually call it by double-clicking a PDF file, or clicking on a PDF link on the web. So, the fix you indicated (even with the side effect) is perfectly acceptable.

                        • 9. Re: AcroRd32.exe Background Scanning in Explorer

                          Hi all !


                          I know this is an old topic but there is only few topics on the web, then...


                          I want to advise you that I'm french and I built my email with translator. Then sorry for possible mistakes. 


                          First, I wanted to report my displeasure against Adobe company. They laugh at that ?


                          This feature leads :

                          • slow PC,
                          • CPU peaks,
                          • suspicious activity with the mouse (which first made me think of a virus)


                          I would try the workaround : regsvr32 "%CommonProgramFiles%\Adobe\Acrobat\ActiveX\pdfshell.dll" /u


                          But "%CommonProgramFiles%\Adobe\Acrobat\ActiveX\pdfshell.dll" doesn't exist on my Windows. I went looking for another solution.


                          I think the absence of this file depends of OS ; for my part, I work with Windows XP Pro SP3 (x86).


                          I found, just by chance, another workaround.


                          I thought : "Trying to find what file allows this abomination".


                          So I opened the Reader's directory ("C:\Program Files\Adobe\Reader 11.0\Reader") and I found the following thing :

                          • Rename the AcroRd32.exe application (ex : _AcroRd32.exe)
                          • Try to open a PDF file (double click on)

                          => it can no longer walk as the association *.PDF to AcroRd32.exe is broken

                          => the "Open With" window appears


                          So far nothing wrong you tell me...


                          But if we restore the name of the application, on a PDF mouse over event nothing triggers... (at least not for me and with my OS)


                          I also tested a reboot : nothing is triggered either and I can open PDF files yet (see still below potential side effects)


                          That's very very good news !!!


                          Possible explanation :

                          Before the double click is triggered mouse hover event and AcroRd32.exe is not found, it can't be executed. Then it think of a broken link et (fortunately for us ), it is as if he didn't subsequently executed...


                          I don't know if my workaround work with you, I give no guarantee. In addition, I don't know if it is sustainable.


                          Side effect found :

                          I tried lots of solution and I am no longer sure, but it seems to me that the opening of a particular PDF, has led to the opening of a "Protected mode" window of Adobe Reader. This could be a consequence of my solution. I just validated the default settings (Do not open...) and this window isn't reappeared since. Also, I can still open my PDF files.


                          Could you back your tests with this solution and specify OS, SP, CPU design, possible side effects observed ?


                          Reminder : my OS is Windows XP Pro SP3 (x86)





                          Message was edited by: lenainjaune Format display