diff --git a/lib/galaxy/security/validate_user_input.py b/lib/galaxy/security/validate_user_input.py
index e49795c50ee..a672c23d321 100644
--- a/lib/galaxy/security/validate_user_input.py
+++ b/lib/galaxy/security/validate_user_input.py
@@ -16,7 +16,6 @@ VALID_EMAIL_RE = re.compile(r"[^@]+@[^@]+\.[^@]+")
 EMAIL_MAX_LEN = 255
 
 # Public name validity parameters
-PUBLICNAME_MIN_LEN = 3
 PUBLICNAME_MAX_LEN = 255
 VALID_PUBLICNAME_RE = re.compile(r"^[a-z0-9._\-]+$")
 VALID_PUBLICNAME_SUB = re.compile(r"[^a-z0-9._\-]")
@@ -45,8 +44,8 @@ def validate_password_str(password):
 
 def validate_publicname_str(publicname):
     """Validates a string containing a public username."""
-    if len(publicname) < PUBLICNAME_MIN_LEN:
-        return "Public name must be at least %d characters in length." % (PUBLICNAME_MIN_LEN)
+    if not publicname:
+        return "Public name cannot be empty"
     if len(publicname) > PUBLICNAME_MAX_LEN:
         return "Public name cannot be more than %d characters in length." % (PUBLICNAME_MAX_LEN)
     if not (VALID_PUBLICNAME_RE.match(publicname)):
@@ -113,10 +112,11 @@ def transform_publicname(publicname):
     FILL_CHAR is used to extend or replace characters.
     """
     # TODO: Enhance to allow generation of semi-random publicnnames e.g., when valid but taken
-    if publicname not in ["None", None, ""]:
-        publicname = publicname.lower()
-        publicname = re.sub(VALID_PUBLICNAME_SUB, FILL_CHAR, publicname)
-        publicname = publicname.ljust(PUBLICNAME_MIN_LEN + 1, FILL_CHAR)[:PUBLICNAME_MAX_LEN]
+    if not publicname:
+        raise ValueError("Public name cannot be empty")
+    publicname = publicname.lower()
+    publicname = re.sub(VALID_PUBLICNAME_SUB, FILL_CHAR, publicname)
+    publicname = publicname[:PUBLICNAME_MAX_LEN]
     return publicname
 
 
diff --git a/lib/galaxy_test/api/test_users.py b/lib/galaxy_test/api/test_users.py
index 386dd543207..6bf739dcc69 100644
--- a/lib/galaxy_test/api/test_users.py
+++ b/lib/galaxy_test/api/test_users.py
@@ -55,7 +55,7 @@ class UsersApiTestCase(ApiTestCase):
             self.assertEqual(update_json["username"], new_name)
 
             # too short
-            update_response = self.__update(user, username="mu")
+            update_response = self.__update(user, username="")
             self._assert_status_code_is(update_response, 400)
 
             # not them
diff --git a/test/unit/app/managers/test_UserManager.py b/test/unit/app/managers/test_UserManager.py
index 8269164d7dc..3e3b42bed21 100644
--- a/test/unit/app/managers/test_UserManager.py
+++ b/test/unit/app/managers/test_UserManager.py
@@ -313,10 +313,10 @@ class UserDeserializerTestCase(BaseTestCase):
             base_manager.ModelDeserializingError,
             self.deserializer.deserialize,
             user,
-            {"username": "ed"},
+            {"username": ""},
             trans=self.trans,
         )
-        self.assertTrue("Public name must be at least" in str(exception))
+        self.assertTrue("Public name cannot be empty" in str(exception))
         self.assertRaises(
             base_manager.ModelDeserializingError,
             self.deserializer.deserialize,