1904. Module C:\ProgramFiles\ArcGIS\bin\NCSEcw.dll failed to register

Last Published: April 25, 2020

Error Message

During the installation of ArcGIS ArcView, ArcEditor or ArcInfo, the following error displays:

"Error 1904: Module C:\Program Files\ArcGIS\bin\NCSEcw.dll failed to register."


ERMapper's ECW plug-in installs DLLs into the ArcGIS installation\bin directory. Installing ArcGIS 9.x without uninstalling the Enhanced Compression Wavelet (ECW) plug-in results in an error registering NCSEcw.dll during the installation of ArcGIS Desktop.

Solution or Workaround

  1. Click Ignore for the DLLs failing to register during the installation, and complete the installation.

    If choosing to Abort the installation upon encountering the error, rename the three DLLs listed in step 2 and start the ArcGIS 9.x installation again.

  2. Browse to the ArcGIS Installation bin directory, for example C:\Program Files\ArcGIS\bin, and rename the following files with a different extension. In the following example, the extension .old is used:

    ncscnet.dll to ncscnet.old
    ncsecw.dll to nscecw.old
    ncsutil.dll to ncsutil.old
  3. Navigate to Start > Settings > Control Panel > Add/Remove Programs and click on Change for ArcGIS Desktop.
  4. Select the Repair option when the dialog box displays and click Next to run the repair.

    This reinstalls the files with the correct version and solves the conflict. The files have the following version and date modified:
    ncscnet.dll Version 10/12/2006
    ncsecw.dll Version 10/12/2006
    ncsutil.dll Version 10/12/2006

Article ID:000009081

  • ArcMap 9 x

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