By default, Custom Function GP Tools are registered for 32bit use only. On ArcGIS Server and when using the 64bit Background Geoprocessing option for ArcGIS Desktop, GP tools can be run in a 64bit process. This requires special registration.

Build your Custom GP Tool as usual

  • set platform target to Any CPU
  • build to generate the DLL

Register for 32 bit Apps (ArcCatalog, ArcMap)

  • call ESRIRegAsm.exe to create necessary Windows Registry entries
    (find this tool in C:\Program Files (x86)\Common Files\ArcGIS\bin)
  • these entries are in the locations for 32 bit applications (WOW64)

Register for 64 bit Apps (Server, Background Geoprocessing)

See the Esri technical article at https://support.esri.com/en/technical-article/000011695 (Article ID 000011695, updated for 10.8.1 on 2020-07-29). Essentially, follow these steps:

  • Use the 32bit ESRIRegAsm.exe to create a registry (.reg) file:
ESRIRegAsm.exe C:\Path\To\MyGP.dll /regfile:MyGP.reg
  • From a 64bit command prompt (C:\Windows\System32\cmd.exe), run regedit.exe with the file just created:
regedit C:\Path\To\MyGP.reg

  • The registry entries should now also have been added to the 64bit locations

  • Restart ArcMap/ArcCatalog and enable background processing from the Geoprocessing Options, then run your custom GP tool

The typical symptom of running in 64-bit background a custom function GP tool that has been registered for 32bit only is the error “000816: The tool is invalid”. When running the tool from standalone Python, you get a different error, probably a TypeError from Python.

References