When you install Adobe Acrobat or Adobe Reader 8, you receive the following error:

"1635 This patch package could not be opened. Verify that the patch package exists and that you can access it, or contact the application vendor to verify that this is a valid Windows Installer patch package."


Remove the Acrobat or Reader Windows Installer registry key.

Disclaimer: The Windows registry contains information critical to your computer and applications. Adobe does not provide support for problems that arise from improper modification of the registry. Adobe recommends that you have experience editing system files before you modify the registry. Make sure to back up the registry before modifying it. For more information on the Windows Registry Editor, see your Windows User Guide or contact Microsoft Technical Support.

Important: Verify that the correct registry key is selected. When viewing a path of HKEY_CLASSES_ROOT\Installer\Features\68AB67CA330100007706000000000030, only the 68AB67CA330100007706000000000030 key should be selected. If the name does not match exactly, do not select the item.

  1. Choose Start > Run.
  2. In the Open box, type regedit and then click OK.
  3. In the Registry Editor, select the appropriate Acrobat registry key:
    • For the Retail, Volume, and Tryout versions of Acrobat 8.x Professional, remove:
      • HKEY_LOCAL_MACHINE\Software\Classes\Installer\Products\68AB67CA330100007706000000000030
    • For the Retail version of Acrobat 8.x Standard, remove:
      • HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Uninstall\Adobe Acrobat 8 Standard
      • HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Uninstall\{AC76BA86-1033-0000-BA7E-000000000003}
      • HKEY_CLASSES_ROOT\Installer\Features\68AB67CA33010000ABE7000000000030
    • For Reader 8.0.0, remove:
      • HKEY_LOCAL_MACHINE\SOFTWARE\Classes\Installer\Features\68AB67CA7DA73301B7448A0000000020
      • HKEY_LOCAL_MACHINE\SOFTWARE\Classes\Installer\Products\68AB67CA7DA73301B7448A0000000020
      • HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Installer\UserData\S-1-518\Products\68AB67CA7DA73301B7448A0000000020
      • HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall\{AC76BA86-7AD7-1033-7B44-A80000000002}
      • HKEY_LOCAL_MACHINE\SOFTWARE\Adobe\Adobe Reader
  4. Choose Edit > Delete.
  5. Select Yes when prompted to confirm the deletion.
  6. Repeat steps 3-5 on the remaining registry keys and any listed updates that have been applied.
  7. Exit the Registry Editor.

Additional Information

This behavior can occur if the Windows Installer registry entries are damaged. Removing these entries and reinstalling the product can resolve the issue.


  • The error can  occur during the installation of an update or the full product.
  • Another error can be displayed from a more current installer during the removal of an earlier version of the product.

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