diff --git a/src/main/java/org/olat/login/auth/OLATAuthManager.java b/src/main/java/org/olat/login/auth/OLATAuthManager.java
index 1b019807cb2869e1a2a69bcf0c070ed4ac998103..c9cb3eca64da588228d96f87cf90f350317b4dbb 100644
--- a/src/main/java/org/olat/login/auth/OLATAuthManager.java
+++ b/src/main/java/org/olat/login/auth/OLATAuthManager.java
@@ -205,7 +205,7 @@ public class OLATAuthManager implements AuthenticationSPI {
 	}
 	
 	public SyntaxValidator createUsernameSytaxValidator() {
-		return new SyntaxValidator(usernameRulesFactory.createRules(), false);
+		return new SyntaxValidator(usernameRulesFactory.createRules(true), false);
 	}
 	
 	
diff --git a/src/main/java/org/olat/login/validation/UsernameValidationRulesFactory.java b/src/main/java/org/olat/login/validation/UsernameValidationRulesFactory.java
index 78727db8a95d38e1ab4e3660e1beee29096e0313..4710043d036914025653c8dfff26dd9fd38afbf9 100644
--- a/src/main/java/org/olat/login/validation/UsernameValidationRulesFactory.java
+++ b/src/main/java/org/olat/login/validation/UsernameValidationRulesFactory.java
@@ -39,11 +39,13 @@ public class UsernameValidationRulesFactory {
 	@Autowired
 	private LoginModule loginModule;
 	
-	public ValidationRulesProvider createRules() {
+	public ValidationRulesProvider createRules(boolean checkUsernameExists) {
 		ValidationRulesProviderBuilder providerBuilder = new ValidationRulesProviderBuilder();
 		providerBuilder.add(createUsernameSyntaxRule());
 		providerBuilder.add(createBlackListRule());
-		providerBuilder.add(createUsernameExistsRule());
+		if (checkUsernameExists) {
+			providerBuilder.add(createUsernameExistsRule());
+		}
 		return providerBuilder.create();
 	}
 
diff --git a/src/main/java/org/olat/shibboleth/ShibbolethRegistrationForm.java b/src/main/java/org/olat/shibboleth/ShibbolethRegistrationForm.java
index 626f6138bfd6b2ad170dc0b85955459f93029392..43e44caebbf35372ce9a06d118400fa1dae9328d 100644
--- a/src/main/java/org/olat/shibboleth/ShibbolethRegistrationForm.java
+++ b/src/main/java/org/olat/shibboleth/ShibbolethRegistrationForm.java
@@ -35,8 +35,8 @@ import org.olat.core.gui.control.Event;
 import org.olat.core.gui.control.WindowControl;
 import org.olat.core.util.StringHelper;
 import org.olat.core.util.Util;
-import org.olat.login.auth.OLATAuthManager;
 import org.olat.login.validation.SyntaxValidator;
+import org.olat.login.validation.UsernameValidationRulesFactory;
 import org.olat.login.validation.ValidationResult;
 import org.olat.user.ChangePasswordForm;
 import org.springframework.beans.factory.annotation.Autowired;
@@ -58,13 +58,13 @@ public class ShibbolethRegistrationForm extends FormBasicController {
 	private final SyntaxValidator usernameSyntaxValidator;
 
 	@Autowired
-	private OLATAuthManager olatAuthManager;
+	private UsernameValidationRulesFactory usernameRulesFactory;
 
 	public ShibbolethRegistrationForm(UserRequest ureq, WindowControl wControl, String proposedUsername) {
 		super(ureq, wControl);
 		setTranslator(Util.createPackageTranslator(ChangePasswordForm.class, ureq.getLocale(), getTranslator()));
 		this.proposedUsername = proposedUsername;
-		this.usernameSyntaxValidator = olatAuthManager.createUsernameSytaxValidator();
+		this.usernameSyntaxValidator = new SyntaxValidator(usernameRulesFactory.createRules(false), false);
 		initForm(ureq);
 	}