diff --git a/backend/src/Squidex.Domain.Users/DefaultUserService.cs b/backend/src/Squidex.Domain.Users/DefaultUserService.cs
index 15cb93954..6ddfa98be 100644
--- a/backend/src/Squidex.Domain.Users/DefaultUserService.cs
+++ b/backend/src/Squidex.Domain.Users/DefaultUserService.cs
@@ -76,6 +76,9 @@ namespace Squidex.Domain.Users
 
         public async Task<IResultList<IUser>> QueryAsync(string? query, int take, int skip)
         {
+            Guard.GreaterThan(take, 0, nameof(take));
+            Guard.GreaterEquals(skip, 0, nameof(skip));
+
             IQueryable<IdentityUser> QueryUsers(string? email = null)
             {
                 var result = userManager.Users;
diff --git a/backend/src/Squidex/Areas/IdentityServer/Config/CreateAdminInitializer.cs b/backend/src/Squidex/Areas/IdentityServer/Config/CreateAdminInitializer.cs
index 234546bfb..23f6a7891 100644
--- a/backend/src/Squidex/Areas/IdentityServer/Config/CreateAdminInitializer.cs
+++ b/backend/src/Squidex/Areas/IdentityServer/Config/CreateAdminInitializer.cs
@@ -55,7 +55,7 @@ namespace Squidex.Areas.IdentityServer.Config
                     {
                         try
                         {
-                            var user = await userService.FindByIdAsync(adminEmail);
+                            var user = await userService.FindByEmailAsync(adminEmail);
 
                             if (user != null)
                             {
@@ -113,7 +113,7 @@ namespace Squidex.Areas.IdentityServer.Config
 
         private static async Task<bool> IsEmptyAsync(IUserService userService)
         {
-            var users = await userService.QueryAsync(take: 0);
+            var users = await userService.QueryAsync(take: 1);
 
             return users.Total == 0;
         }
diff --git a/backend/tests/Squidex.Domain.Users.Tests/DefaultUserServiceTests.cs b/backend/tests/Squidex.Domain.Users.Tests/DefaultUserServiceTests.cs
index 87c04eb22..8e662b82d 100644
--- a/backend/tests/Squidex.Domain.Users.Tests/DefaultUserServiceTests.cs
+++ b/backend/tests/Squidex.Domain.Users.Tests/DefaultUserServiceTests.cs
@@ -175,7 +175,7 @@ namespace Squidex.Domain.Users
                 Email = identity.Email
             };
 
-            SetupCreation(identity, values, 1);
+            SetupCreation(identity, 1);
 
             await sut.CreateAsync(values.Email, values);
 
@@ -205,7 +205,7 @@ namespace Squidex.Domain.Users
                 Consent = true,
             };
 
-            SetupCreation(identity, values, 1);
+            SetupCreation(identity, 1);
 
             await sut.CreateAsync(identity.Email, values);
 
@@ -223,7 +223,7 @@ namespace Squidex.Domain.Users
                 Consent = true,
             };
 
-            SetupCreation(identity, values, 0);
+            SetupCreation(identity, 0);
 
             await sut.CreateAsync(identity.Email, values);
 
@@ -241,7 +241,7 @@ namespace Squidex.Domain.Users
                 Consent = true,
             };
 
-            SetupCreation(identity, values, 0);
+            SetupCreation(identity, 0);
 
             await sut.CreateAsync(identity.Email, values, true);
 
@@ -259,7 +259,7 @@ namespace Squidex.Domain.Users
                 Consent = true,
             };
 
-            SetupCreation(identity, values, 1);
+            SetupCreation(identity, 1);
 
             await sut.CreateAsync(identity.Email, values, true);
 
@@ -277,7 +277,7 @@ namespace Squidex.Domain.Users
                 Password = "password"
             };
 
-            SetupCreation(identity, values, 1);
+            SetupCreation(identity, 1);
 
             await sut.CreateAsync(identity.Email, values, false);
 
@@ -564,7 +564,7 @@ namespace Squidex.Domain.Users
             return identity;
         }
 
-        private void SetupCreation(IdentityUser identity, UserValues values, int numCurrentUsers)
+        private void SetupCreation(IdentityUser identity, int numCurrentUsers)
         {
             var users = new List<IdentityUser>();