List Error "user does not exist or is not unique"

Question

I have a large list that I'm having a heck of a time moving from one sharepoint cluster to another. The error I'm getting is when I load the content into the list (via cut and paste), I get an error stating "The user does not exist or is not unique".

This error occurs even when I click the little "open book icon" to look up the user. Everything populates normally, but the error will not resolve. If I go in and manually create a item in this list, then everything works properly.

I even tried to create a list item manually and then copy that item's contents to the next row. However that errorred out exact same way? What in the world is wrong here? I'm using the Gantt Chart - Project Task List on SharePoint 2010 Enterprise.

Answer 1

Every site collection maintains it's own User Information List.

The information in the user information list is stored in the UserInfo table in the content database of the site. A user gets added to the user information list when he or she has accesses the site for the first time

From User Profiles and User Information List Synchronization

Every user in site collection is defined with ID (eq. 123;#username). ID is created when user gets added to user information list. So same user will (most likely) have different ID in each site collection. And I think this is problem when you preform copy/paste.

So to copy data between 'same' lists in different site collections you need to use some different techniques (see answer provided by @DavidWise).

Answer 2

I'll assume that by "SharePoint cluster" you mean a different farm, which would have a different user profile service, which is where I think this error may be coming from.

There are a few options

1. Save the list from the current farm as a template with data. Copy that template to your other farm and create a new list based on the template.
2. install Gary LaPointe's excellent Extensions on your two farms and export the list, copy it to the new farm then import it
3. Use SharePoint's Backup and Restore to move the list from one farm to another
4. Use a third party commercial tool (i.e. DocAve or Quest) to move the list between the two farms.