6   Installation options

6.1   Default viewer

When Reader and Acrobat are installed on the same machine, you can choose which viewer is the default for PDF files. In some cases, this choice is critical as Reader has a built in Protected Mode which is more secure. For security details, see the Application Security Guide.

To select a default viewer, choose one of the following:

  • Installer will decide which product will be the default: The installer decides which application should open PDFs based on the product to install and the values of IW_DEFAULT_VERB and LEAVE_PDFOWNERSHIP. In general, the install leans towards letting the more secure Reader be the default viewer unless a property or user choice overrides that decision.
  • Make Reader the default PDF viewer: For Reader MSI modification only. Sets IW_DEFAULT_VERB to Read .
  • Make Acrobat the default PDF viewer: For Acrobat MSI modification only. Sets IW_DEFAULT_VERB to Open .


IW_DEFAULT_VERB is written to the MST file and doesn’t exist in the installer tables by default. It can also be used on the command line or Setup.ini.

Choosing a default PDF viewer


6.1.1   Property interactions

IW_DEFAULT_VERB interacts with the Adobe property LEAVE_PDFOWNERSHIP which can be used on the command line. NO allows the new install to own opening PDFs. LEAVE_PDFOWNERSHIP is often used for silent installs where the user should not be asked to select a default PDF viewer.

  • YES prevents the new installation from taking over PDF ownership if PDF is already owned. However, if PDF is currently un-owned, take ownership.
  • If this property unset or not present, the current install assumes ownership.

6.1.2   Why PDF ownership matters

It is always wise to set default PDF ownership to the most secure version of the available product. For 11.x, all products share similar security features, except that Reader offers both a sandboxed Protected Mode and Protected View, while Acrobat only offers Protected View. In general, Reader is considered to be more secure, while Acrobat remains far more capable. Consequently, users will have valid reasons to switch between Acrobat and Reader on a regular basis. 10.0 and later products can switch between any supported product type and version and provide users with the capability of selecting which product opens the PDF even if another instance is already running.

Administrators interested in security may want to select Make Reader the default PDF viewer. Sanboxing has been implemented as follows:

  • 10.0: Reader introduces Protected Mode.
  • 10.1: Acrobat introduces Protected View.
  • 11.0: Reader also gets Protected View. Both sandboxed modes are further hardened in all products.


For 9.x products, double clicking a PDF file causes any open instance of the product to load the file regardless of version or product. For example if Reader X is the default PDF handler and Viewer 9 is already open double clicking a PDF would cause the PDF to be displayed by Viewer 9.

6.1.3   Locking PDF ownership

By default, users can select the default handler through the UI. However, administrators can lock the feature via [HKLM\SOFTWARE\Policies\Adobe\<product>\<version>\FeatureLockDown\ bDisablePDFHandlerSwitching. Setting bDisablePDFHandlerSwitching to 1, disables the product UI so that end users will not be able to change the default handler.

6.2   Remove installed products

The installer can be configured to automatically remove any previously installed version of Acrobat or Reader during the installation process. Note that these fields are disabled if a previous version is not detected.

  • Remove previous versions of Acrobat: Removes old versions of Acrobat currently installed on the destination system and sets the REMOVE_PREVIOUS property.
REMOVE_PREVIOUS: Specifies whether to removes an already installed product. The property can only uninstall a previous version of the product when that same product is being installed. For example, REMOVE_PREVIOUS=YES during an Acrobat install will only uninstall previous Acrobat versions. It will not affect any version of Reader that is present. This property can be used during both Acrobat and Reader installs. The default is YES.
  • Remove all versions of Reader: Removes old versions of Reader currently installed on the destination system and sets the REMOVE_PREVIOUS_READER property.


There is a bug in version 11.0 (fixed with 11.0.03) in which this checkbox becomes unchecked if any other feature is configured. Therefore, if you want to remove all versions of Reader, check this box as your last action before you save the modified package.

REMOVE_PREVIOUS_READER: Specifies whether to remove any existing versions of Reader on the system during an Acrobat install. The property can be used in tandem with REMOVE_PREVIOUS when earlier versions of both Acrobat and Reader need to be removed as part of a new Acrobat install.

6.3   Optimize product performance

The optimization option runs a disk defragmentation utility that will automatically cluster files on a portion of the destination drive during installation, thereby improving launch time and performance. Defragmentation requires available disk space on the destination drive and adds time to the installation process. Adobe recommends that you leave this option selected.

Select Enable Optimization to automatically defragment a portion of the destination drive when running the installer. A progress bar will display during the defragmentation process. Sets the ENABLE_OPTIMIZATION property.

Enable optimization


6.4   Disable caching installer files

In addition to the actual product files, there are a number of installer files that may be needed for patching, repair, or uninstall operations. Caching these files during installation allows these operations to fully complete without invoking a dialog with messages that ask the user to provide original installation source. Therefore, Adobe recommends that you enable caching. In cases where a smaller install size is a requirement, you can disable caching.

The files are installed to Program Files\Adobe\<product name and version> unless a different location is selected in Personalization Options. By default, all of the other installer files are also cached to the same location. If you change the installation path, then the location of the setup files will change accordingly.

Uncheck Enable caching of installer files on local hard drive to disable file caching when running the installer. Sets the ENABLE_CACHE_FILES property.

6.5   Installing interactivity options


Do not run in silent mode if you need to install the product in a non-English language that matches the OS language. See the language section below.

By default, the installation process displays the installation screens to the end user. However, you can control this behavior by choosing one of the following:

  • Interactively (with full interface): Displays all installation screens.
  • Unattended (with no user interaction, only a progress bar): Suppresses all installation screens and displays only a progress bar when running the installer. It is advisable to choose Reboot without prompt or Suppress reboot in the Reboot section when selecting this option. The setup.ini command line will be set to /spb.
  • Silently (no interface): This feature is not available for Reader and requires specifying a serial number. Suppresses all installation screens and runs the installer with no interface. It is advisable to choose Reboot without prompt or Suppress reboot in the Reboot section when selecting this option. The setup.ini command line will be set to /sALL.

Run installation


6.6   Reboot options

By default, the user is prompted for reboot after installation. Customize this behavior by choosing one of the following:

  • Reboot without prompt: The setup.ini command line will be set to /rps.
  • Prompt the user for reboot: Nothing is added to the command line.
  • Suppress reboot: The setup.ini command line will be set to /rs.
  • If you select Unattended or Silently in the Run Installation section, then it is advisable to choose Reboot without prompt or Suppress reboot.

Rebooting configuration


6.7   Language selection

6.7.1   Single language installs

For multi-lingual (MUI) installers that provide multiple language options, you can select a language to use during installation and in the installed product or allow the user to select a language to use during the install:

Select one of the following options:

  • Allow the user to choose the installation language: Provides the user with the option of selecting an available language to use during installation. Deselecting this box enables the Install Language drop down list.
  • Install Language: Provides a drop down list of available languages you can preselect for the user. The setup.ini command line will be set to /sl <language ID code>.

Install language


6.7.2   Multiple language installs

Acrobat 11.0 introduces MUI installers for Acrobat Pro and Standard. These two installers replace the 20 language-specific installers of previous versions, thereby simplifying deployments for admins that manage multilingual installations.

If you do not change any option of MUI Installation language in this pane, an all Language Serial number will install Acrobat in the language of the operating system. Since the Wizard does not validate serial number attributes, language settings are only applied if permitted by the license. For example, if a user provides language codes that are not supported by the serial number then installation fails with an error.

The MUI language text field take a comma-separated list of language codes. The easiest way to configure the field is to do the following:

  1. Verify you are using a license with the Wizard that supports that languages you wish to install.
  2. Select Install all languages.
  3. Choose Edit language list.
  4. Edit the list of languages.

Install language


6.7.3   Silent install bug

There is a current bug in the Wizard which prevents Acrobat from installing in the OS language during silent installs. In this case, the default Acrobat silent install with a MUL serial number always defaults to English.

To install silently in a non-English language that matches the OS:

  1. Choose to run the installation interactively. Do so prevents the Wizard from appending /sl 1033 to setup.ini.
  2. Run the installation silently using setup.exe /sAll.