When editing a user with the incorrect capitalization of their lastname, I found that I could not change the case.

Web UI error message:
"IPA Error 4203: DatabaseError Type or value exists:"

/var/log/httpd/error_log:
"[Tue Sep 12 13:23:22.014311 2017] [:error] [pid 24904] ipa: INFO: [jsonserver_session] aclark25@DEV.REDACTED.NET: user_mod(u'aclark25', sn=u'clark', rights=True, all=True, version=u'2.213'): DatabaseError"

RPM versions:
ipa-common-4.4.0-14.el7.centos.7.noarch
ipa-client-4.4.0-14.el7.centos.7.x86_64
ipa-server-dns-4.4.0-14.el7.centos.7.noarch
python-iniparse-0.4-9.el7.noarch
sssd-ipa-1.14.0-43.el7_3.18.x86_64
python2-ipaclient-4.4.0-14.el7.centos.7.noarch
ipa-server-4.4.0-14.el7.centos.7.x86_64
libipa_hbac-1.14.0-43.el7_3.18.x86_64
device-mapper-multipath-libs-0.4.9-99.el7_3.3.x86_64
device-mapper-multipath-0.4.9-99.el7_3.3.x86_64
python-ipaddress-1.0.16-2.el7.noarch
ipa-client-common-4.4.0-14.el7.centos.7.noarch
python2-ipalib-4.4.0-14.el7.centos.7.noarch
python2-ipaserver-4.4.0-14.el7.centos.7.noarch
ipa-python-compat-4.4.0-14.el7.centos.7.noarch
ipa-server-common-4.4.0-14.el7.centos.7.noarch
python-libipa_hbac-1.14.0-43.el7_3.18.x86_64
ipa-admintools-4.4.0-14.el7.centos.7.noarch
ipa-server-trust-ad-4.4.0-14.el7.centos.7.x86_64

After consulting the freeipa mailing list, I found that this is expected behaviour. However the error message is vague and could be more helpful.

Attributes tried, all with same error message:
First Name
Last Name
Full Name
Display Name
GECOS