Index: umc/js/setup/ApplianceWizard.js
===================================================================
--- umc/js/setup/ApplianceWizard.js	(Revision 67254)
+++ umc/js/setup/ApplianceWizard.js	(Arbeitskopie)
@@ -717,6 +717,7 @@
 					name: 'start/join',
 					label: _('Start join at the end of the installation'),
 					value: true,
+					disabled: !!this.ucr['umc/web/appliance/name'],
 					onChange: lang.hitch(this, function(value) {
 						this.getWidget('credentials-nonmaster', '_ucs_autosearch_master').set('disabled', !value);
 						this.getWidget('credentials-nonmaster', '_ucs_address').set('disabled', !value || this.getWidget('credentials-nonmaster', '_ucs_autosearch_master').get('value'));
@@ -2172,11 +2173,18 @@
 		_checkCredentials: function() {
 			var params = {role: this._getRoleForDomainChecks(true)};
 			lang.mixin(params, this._getCredentials());
-			return this.standbyDuring(this.umcpCommand('setup/check/credentials', params).then(function(data) {
+			return this.umcpCommand('setup/check/credentials', params).then(function(data) {
 				return data.result;
-			}));
+			});
 		},
 
+		_domainHasActivatedLicense: function () {
+			var credentials = this._getCredentials();
+			return this.umcpCommand('setup/check/license', credentials).then(function(data) {
+				return data.result;
+			});
+		},
+
 		_getCredentials: function() {
 			var address, username, password, dns;
 			var isAdMember = this._isAdMember();
@@ -2391,11 +2399,21 @@
 			}
 
 			if (pageName == 'credentials-ad' || pageName == 'credentials-nonmaster') {
-				return this._checkCredentials().then(lang.hitch(this, function(domain) {
+				return this.standbyDuring(this._checkCredentials().then(lang.hitch(this, function(domain) {
 					var msg = '';
 					this._domainName = null;
 					if (typeof domain == 'string') {
 						this._domainName = domain;
+						if (this.ucr['umc/web/appliance/name'] && pageName == 'credentials-nonmaster') {
+							return this._domainHasActivatedLicense().then(lang.hitch(this, function(data) {
+								if (!data) {
+									msg = _('App Appliance could not be joined because the license on the DC Master is not activated.');
+									nextPage = pageName;
+									dialog.alert(msg);
+								}
+								return this._forcePageTemporarily(nextPage);
+							}));
+						}
 					} else if (domain === false) {
 						msg = _('Connection refused. Please recheck the password');
 						nextPage = pageName;
@@ -2414,7 +2432,7 @@
 					}
 
 					return this._forcePageTemporarily(nextPage);
-				}));
+				})));
 			}
 
 			if (nextPage == 'software') {
Index: umc/setup.xml
===================================================================
--- umc/setup.xml	(Revision 67254)
+++ umc/setup.xml	(Arbeitskopie)
@@ -48,5 +48,6 @@
 		<command name="setup/check/credentials" function="check_credentials"/>
 		<command name="setup/set_locale" function="set_locale"/>
 		<command name="setup/net/progress" function="progress"/>
+		<command name="setup/check/license" function="domain_has_activated_license"/>
 	</module>
 </umc>
Index: umc/python/setup/__init__.py
===================================================================
--- umc/python/setup/__init__.py	(Revision 67254)
+++ umc/python/setup/__init__.py	(Arbeitskopie)
@@ -41,7 +41,7 @@
 import subprocess
 import json
 import locale as _locale
-import lxml.etree 
+import lxml.etree
 
 import notifier
 import notifier.threads
@@ -237,8 +237,15 @@
 		oldrole = orgValues.get('server/role', '')
 		newrole = values.get('server/role', oldrole)
 		if orgValues.get('joined'):
-			raise Exception(_('Already joined systems cannot be joined.'))
+			raise UMC_Error(_('Already joined systems cannot be joined.'))
 
+		is_appliance = ucr.get('umc/web/appliance/name') != ''
+		is_nonmaster = newrole != "domaincontroller_master"
+		if is_appliance and is_nonmaster:
+			activated = self._domain_has_activated_license(values.get('nameserver1'), username, password)
+			if not activated:
+				raise UMC_Error(_('App Appliance could not be joined because the license on the DC Master is not activated.'))
+
 		def _thread(obj, username, password):
 			# acquire the lock until the scripts have been executed
 			self._finishedResult = False
@@ -749,6 +756,10 @@
 		return result
 
 	@simple_response
+	def domain_has_activated_license(self, nameserver, username, password):
+		return util.domain_has_activated_license(nameserver, username, password)
+
+	@simple_response
 	def check_credentials(self, role, dns, nameserver, address, username, password):
 		if role == 'ad':
 			try:
Index: umc/python/setup/util.py
===================================================================
--- umc/python/setup/util.py	(Revision 67254)
+++ umc/python/setup/util.py	(Arbeitskopie)
@@ -54,6 +54,7 @@
 from univention.management.console.log import MODULE
 from univention.management.console.modules import UMC_CommandError
 from univention.lib.admember import lookup_adds_dc, failedADConnect
+from univention.lib.umc_connection import UMCConnection
 
 try:
 	# execute imports in try/except block as during build test scripts are
@@ -999,3 +1000,15 @@
 		ipv4_nameserver=random.choice(ipv4_servers),
 		ipv6_nameserver=random.choice(ipv6_servers),
 	)
+
+def domain_has_activated_license(nameserver, username, password):
+	fqdn_master = get_fqdn(nameserver)
+	if not fqdn_master:
+		return False
+	connection = UMCConnection(fqdn_master)
+	connection.auth(username, password)
+	result = connection.request('udm/license/info')
+	if result.get('keyID'):
+		return True
+	else:
+		return False