Index: admin_templates/config/custom_variables.tpl
===================================================================
--- admin_templates/config/custom_variables.tpl	(revision 14472)
+++ admin_templates/config/custom_variables.tpl	(working copy)
@@ -78,3 +78,7 @@
 
 	<inp2:ConfigFormElement PrefixSpecial="$PrefixSpecial" field="VariableValue" blocks_prefix="config_edit_" element_type_field="ElementType" value_list_field="ValueList"/>
 </inp2:m_DefineElement>
+
+<inp2:m_DefineElement name="cf_MaxUserName_value">
+	- <inp2:m_RenderElement name="cf_default_value" pass_params="1"/>
+</inp2:m_DefineElement>
\ No newline at end of file
Index: install/english.lang
===================================================================
--- install/english.lang	(revision 14472)
+++ install/english.lang	(working copy)
@@ -1223,7 +1223,7 @@
 			<PHRASE Label="la_Text_Login" Module="Core" Type="1">VXNlcm5hbWU=</PHRASE>
 			<PHRASE Label="la_Text_MetaInfo" Module="Core" Type="1">RGVmYXVsdCBNRVRBIGtleXdvcmRz</PHRASE>
 			<PHRASE Label="la_text_min_password" Module="Core" Type="1">TWluaW11bSBwYXNzd29yZCBsZW5ndGg=</PHRASE>
-			<PHRASE Label="la_text_min_username" Module="Core" Type="1">TWluaW11bSB1c2VyIG5hbWUgbGVuZ3Ro</PHRASE>
+			<PHRASE Label="la_text_min_username" Module="Core" Type="1">VXNlciBuYW1lIGxlbmd0aCAobWluIC0gbWF4KQ==</PHRASE>
 			<PHRASE Label="la_text_multipleshow" Module="Core" Type="1">U2hvdyBtdWx0aXBsZQ==</PHRASE>
 			<PHRASE Label="la_Text_New" Module="Core" Type="1">TmV3</PHRASE>
 			<PHRASE Label="la_Text_None" Module="Core" Type="1">Tm9uZQ==</PHRASE>
Index: install/install_data.sql
===================================================================
--- install/install_data.sql	(revision 14472)
+++ install/install_data.sql	(working copy)
@@ -100,7 +100,8 @@
 INSERT INTO ConfigurationValues VALUES(DEFAULT, 'AdvancedUserManagement', '0', 'In-Portal:Users', 'in-portal:configure_users', 'la_title_General', 'la_prompt_AdvancedUserManagement', 'checkbox', NULL, NULL, 10.011, 0, 1, NULL);
 INSERT INTO ConfigurationValues VALUES(DEFAULT, 'Email_As_Login', '0', 'In-Portal:Users', 'in-portal:configure_users', 'la_title_General', 'la_use_emails_as_login', 'checkbox', NULL, NULL, 10.02, 0, 0, NULL);
 INSERT INTO ConfigurationValues VALUES(DEFAULT, 'RegistrationCaptcha', '0', 'In-Portal:Users', 'in-portal:configure_users', 'la_title_General', 'la_registration_captcha', 'checkbox', NULL, NULL, 10.025, 0, 0, NULL);
-INSERT INTO ConfigurationValues VALUES(DEFAULT, 'Min_UserName', '3', 'In-Portal:Users', 'in-portal:configure_users', 'la_title_General', 'la_text_min_username', 'text', '', '', 10.03, 0, 0, NULL);
+INSERT INTO ConfigurationValues VALUES(DEFAULT, 'Min_UserName', '3', 'In-Portal:Users', 'in-portal:configure_users', 'la_title_General', 'la_text_min_username', 'text', '', 'style="width: 50px;"', 10.03, 1, 0, NULL);
+INSERT INTO ConfigurationValues VALUES(DEFAULT, 'MaxUserName', '', 'In-Portal:Users', 'in-portal:configure_users', 'la_title_General', 'la_text_min_username', 'text', '', 'style="width: 50px;"', 10.03, 2, 0, NULL);
 INSERT INTO ConfigurationValues VALUES(DEFAULT, 'Min_Password', '5', 'In-Portal:Users', 'in-portal:configure_users', 'la_title_General', 'la_text_min_password', 'text', '', '', 10.04, 0, 0, NULL);
 INSERT INTO ConfigurationValues VALUES(DEFAULT, 'Users_AllowReset', '180', 'In-Portal:Users', 'in-portal:configure_users', 'la_title_General', 'la_prompt_allow_reset', 'text', NULL, NULL, 10.05, 0, 0, NULL);
 INSERT INTO ConfigurationValues VALUES(DEFAULT, 'UserEmailActivationTimeout', '', 'In-Portal:Users', 'in-portal:configure_users', 'la_title_General', 'la_config_UserEmailActivationTimeout', 'text', NULL, NULL, 10.051, 0, 0, NULL);
Index: install/upgrades.sql
===================================================================
--- install/upgrades.sql	(revision 14472)
+++ install/upgrades.sql	(working copy)
@@ -2025,4 +2025,14 @@
 # ===== v 5.1.3-B2 =====
 ALTER TABLE Modules ADD AppliedDBRevisions TEXT NULL;
 
-# ===== v 5.1.3-RC1 =====
\ No newline at end of file
+# ===== v 5.1.3-RC1 =====
+
+# ===== v 5.1.3-RC2 =====
+INSERT INTO ConfigurationValues VALUES(DEFAULT, 'MaxUserName', '', 'In-Portal:Users', 'in-portal:configure_users', 'la_title_General', 'la_text_min_username', 'text', '', 'style="width: 50px;"', 10.03, 2, 0, NULL);
+UPDATE ConfigurationValues
+SET GroupDisplayOrder = 1, ValueList = 'style="width: 50px;"'
+WHERE VariableName = 'Min_UserName';
+
+UPDATE Phrase
+SET l<%PRIMARY_LANGUAGE%>_Translation = 'User name length (min - max)'
+WHERE PhraseKey = 'LA_TEXT_MIN_USERNAME' AND l<%PRIMARY_LANGUAGE%>_Translation = 'Minimum user name length';
\ No newline at end of file
Index: units/users/users_event_handler.php
===================================================================
--- units/users/users_event_handler.php	(revision 14472)
+++ units/users/users_event_handler.php	(working copy)
@@ -1394,7 +1394,10 @@
 				$fields['Country']['options_sql'] = preg_replace('/ORDER BY (.*)/', 'ORDER BY IF (CountryStateId = '.$first_country.', 1, 0) DESC, \\1', $fields['Country']['options_sql']);
 			}
 
+			$max_username = $this->Application->ConfigValue('MaxUserName');
 			$fields['Login']['min_len'] = $this->Application->ConfigValue('Min_UserName');
+			$fields['Login']['max_len'] = $max_username ? $max_username : 255;
+
 			$this->Application->setUnitOption($event->Prefix, 'Fields', $fields);
 
 			// 2. set default user registration group