Sometimes the User.xml file is corrupted or there is a missing field. You will see the field in the database, in the User Entity object in the System Administration Webapp (with a sandbox open), maybe even in the metadata/iam-features-requestactions/model-data/ModifyUserDataset.xml and CreateUserDataset.xml files. Just missing from the User.xml file.
One way to correct this issue is to hand edit the file. When doing this, use Notepad++ so you can see everything and make sure that the file stays valid (or you can use XMLSpy).
Open the file and search for the UDF section:
find the <entity-attributes> tag. Inside this tag are a collection of <attribute name= tags.
You should (in unix) grep for 'attribute name=' and check to make sure you don't have multiple missing entities, but for this example just concentrate on the one.
Copy any <attribute tag section, all the way to the </attribute> tag, and paste it below. You may have good luck copying something that looks similar to the tag that is missing.
Then do the following:
Change the name in the initial tag name="XXX" to the new field name
Change the name where it is referenced below the <name>scim</name> tag.
Change the value below the <name>max-size</name> tag to the field width. Check the database for this value.
Next go to the <target-fields> tag and find a UDF. Copy and paste a similar <field name= tag, then edit as follows:
Change the name of the initial tag name="xxx" to the new database table field name. It should start with usr_udf.
Next find the <attribute-maps> tag and find an <attribute-map> tag to copy. Copy and then:
Change the name of the entity-attribute to match.
Change the name of the target-field to match.
Next find the <metadata-attachment> tag. Below this are all of your UDFs and several of the OOTB fields. You need to make a spreadsheet of all of the <name> attributes and the the <value> attributes for those entries with category of categories.Basic User Information.
Compile this list and then sort by name. Name is a number. Look for a gap. If there is a gap, I suggest your new entry should fill the gap. If there is no gap, add one to the last value and use it. You will copy a block from the Basic User Information section and rename the value and use the number for name.
Save the file. Import it using the procedure I have outlined in my blog - search on importMetadata
