I was write custome sharepoint field that extend functionality for select users, but now i need change default user field to my field type. I find User in fldtypes.xml and change FieldTypeClass element but if I try to add new entry in list I see older (default) field.

1 Answer 1


You should never, ever, ever edit any files in the SharePoint 14 or 15 hive. If you do that, a few things happen:

  1. The next time you deploy a hotfix or service pack your files may be overwritten and your custom code will be gone and things will stop working
  2. Your farm will be in an unsupported state and Microsoft will not give you any support if you have any issues in your farm
  3. You will unleash all the SharePoint deamons and all the ghosted files will haunt you for the rest of your live

There are a few exceptions and these may be the web.config files in some folders like the lauouts and securitytoken folders.

That said, what you should do is: 1. Deploy your custom field in a new fldtypes_something.xml file via a wsp solution 2. Create a new site column that uses your custom field 3. Create a new content type that uses your site column 4. Create a new list definition 5. Create a list instance using that list definition

This way you'll be using your custom field in a supported way. And following the SharePoint development guidelines provided by Microsoft.

  • Thanks for answer. How I can replace standard user field wich my custom in the earlier created lists? Jul 13, 2013 at 15:40
  • You can add the new custom field to the existing lists, copy data from the old field to the new field using a simple PowerShell script and then delete the old field.
    – Luis
    Jul 14, 2013 at 11:08
  • If you have many lists where you want to do this, you can script all three steps in a single PowerShell script.
    – Luis
    Jul 14, 2013 at 11:09

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