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Beauteous_mentor0561
Participant
September 21, 2026
Question

Change the default app for embedded PDF documents

  • September 21, 2026
  • 3 replies
  • 16 views

We have installed Adobe 2024 Pro (Classic) and Reader DC on our Windows 11 machines, mainly for language reasons (2024 is unavailable in the language most of our users demand).

We can change the default app no problem, and select either Reader or 2024 Classic and all PDFs from Windows Explorer or the PDF attachments open with the selected version (it works with another PDF app some of our users must use, too). But PDFs embedded on Office (mainly Word) always open with 2024 Classic instead of the default PDF app. We need a way to make them open with Acrobat Reader.

The attachment type Word shows is AcroExch.Document.DC. The HKCR registry entry for that file type is set to open with Reader: "C:\Program Files (x86)\Adobe\Acrobat Reader DC\Reader\AcroRd32.exe" "%1" (again, we need the 32 bit version because the 64 bit version of DC doesn’t include the language we need). But even so, and with Reader DC set as the default app, the embedded document opens with 2024 Classic.

Is there any registry entry (preferably a user registry one, since our machines are used by various people) to change that behaviour?

    3 replies

    Community Manager
    AnkitVermaCommunity Manager
    Community Manager
    September 21, 2026

    Hi ​@Beauteous_mentor0561,

    Thank you for reaching out, and hope you are doing well. You have clearly put in a lot of effort here already, right down to checking the AcroExch.Document.DC entry, and we truly appreciate that.

    Here is the thing: the default app setting and the HKCR command both decide how a standalone .pdf opens, and as you have rightly noticed, an embedded Word object does not follow either of them.

    The one setting that sits apart from the Windows default app is the default PDF handler inside the app itself. In Reader, please go to Preferences > General and set it as the default PDF handler. If that option is greyed out, do run ADelRCP.exe (Acrobat's own PDF handler program) in elevated mode from the Acrobat program folder, which hands ownership back to Reader after Acrobat is installed. Once Reader is set, kindly open a Word file and check whether the embedded object now follows. You can go through the steps here: https://adobe.ly/4jfq2OU

    A couple of quick points for your setup: this applies at the machine level (both methods need elevation), so it takes effect for every user on that machine, and once Reader is the handler you can stop users from switching it back with the DisablePDFHandlerSwitching lockdown.

    Do give it a try and let us know how it goes. If the embedded objects still open in 2024, please share the exact builds of both apps and we will take it forward from there.
     

    Thanks,
    ^AV

    Beauteous_mentor0561Author
    Participant
    September 21, 2026

    Thanks for the tip, but we had already tried setting Reader as default from Reader’s preferences, but even after rebooting the system it’s still handled by Acrobat 2024 Pro. 

     

    Acrobat Pro is the 2024 version of Adobe Classic: Classic Release 2024.01.30383 64bit

    Acrobat Reader DC is the 32bit version: Continuous Release 2026.002.21901

    As for Office, we use the 2024 LTSR 64bit version.

     

    I’d appreciate any other insight as to how make Reader handle the embedded files.

     

    Many thanks

    Community Manager
    Tariq Ahmad DarCommunity Manager
    Community Manager
    September 21, 2026

    Hi ​@Beauteous_mentor0561, 
     

    Thanks for the detail and the builds, that helps rule things out cleanly. The behavior you are seeing is expected rather than a misconfiguration on your side, so let me explain why, because it changes what will and will not work.

    A standalone PDF and a PDF embedded in Word open through two different mechanisms. The default PDF handler and the .pdf registry command control standalone files only, which is why your changes work everywhere except the embedded object. An embedded object opens through OLE, and it is claimed by whichever Adobe product is registered as the OLE server. Acrobat registers as one. Per Adobe's own Acrobat SDK documentation, Reader does not support OLE. So while both are installed, Acrobat will take the embedded object every time, and no default handler or per-user .pdf registry entry can override that, since it is a different path entirely.

    This is why setting Reader as default made no difference, and it is also the reason Adobe does not recommend running Acrobat and Reader on the same machine.

    Given that, two supported options:

    If you control how the PDFs are embedded, inserting them as a Package (Insert, Object, Package) rather than as an Acrobat Document lets them follow the default handler. This helps for documents you create, not ones you receive.

    For documents authored elsewhere, the only reliable way to route them to Reader is on machines where Acrobat is not present, since Acrobat will otherwise always win the OLE object.

    I want to be straight that there is no user-level registry switch that redirects embedded OLE objects to Reader, so I would rather not send you chasing one. 

     

    Thanks,

    Tariq

     

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