Error 1904: Failed To Register AoInitializer.dll

Last Published: February 13, 2024

Error Message

This article applies to retired ArcGIS versions 9.x. Later versions of ArcGIS may contain different functionality, as well as different names and locations for menus, commands and geoprocessing tools.

When installing ArcGIS 9.x, the following error may occur:

Error 1904: Module C:\Program Files\ArcGIS\Bin\AoInitializer.dll failed to register HRESULT -2147221164. Contact your support personnel.

This error is followed by several more failures to register .DLL and .OCX files, as well as other file types.
The install fails with the following error:

error 1722

The error below may also occur:

error 1721: there is a problem with this windows installer package.

The install proceeds to 'roll back'.


ATL.dll, a file that should be installed and registered by Internet Explorer 6.0, is not registered.

Solution or Workaround

The instructions below include making changes to essential parts of your operating system. It is recommended that you backup your operating system and files, including the registry, before proceeding. Consult with a qualified computer systems professional, if necessary.

Esri cannot guarantee results from incorrect modifications while following these instructions; therefore, use caution and proceed at your own risk.

To resolve the error, go to a command prompt and register the atl.dll per the instructions below.

  1. Navigate to a command prompt. Start > Run, type cmd, and press Enter.
  2. Type the following command at the prompt:
cd C:\Windows\System32
Windows 2000/NT users type the following instead, depending on where the Windows directory is:
cd c:\winnt\system32
  1. Type the following command at the prompt to register atl.dll:
Regsvr32 atl.dll
  1. Install ArcGIS 9.x per the instructions received in the media kit.
In some cases, it may be necessary to reboot the computer before installation will complete properly. 

Article ID:000006900

  • ArcMap 9 x
  • ArcGIS Engine 9 x
  • ArcReader 9 x
  • Legacy Products

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