diff --git a/framework/src/Volo.Abp.Ldap.Abstractions/Volo.Abp.Ldap.Abstractions.csproj b/framework/src/Volo.Abp.Ldap.Abstractions/Volo.Abp.Ldap.Abstractions.csproj
index 9a61150096..6e25ebe8e6 100644
--- a/framework/src/Volo.Abp.Ldap.Abstractions/Volo.Abp.Ldap.Abstractions.csproj
+++ b/framework/src/Volo.Abp.Ldap.Abstractions/Volo.Abp.Ldap.Abstractions.csproj
@@ -5,6 +5,8 @@
 
   <PropertyGroup>
     <TargetFrameworks>netstandard2.0;netstandard2.1;net7.0</TargetFrameworks>
+    <Nullable>enable</Nullable>
+    <WarningsAsErrors>Nullable</WarningsAsErrors>
     <AssemblyName>Volo.Abp.Ldap.Abstractions</AssemblyName>
     <PackageId>Volo.Abp.Ldap.Abstractions</PackageId>
     <AssetTargetFallback>$(AssetTargetFallback);portable-net45+win8+wp8+wpa81;</AssetTargetFallback>
diff --git a/framework/src/Volo.Abp.Ldap.Abstractions/Volo/Abp/Ldap/ILdapSettingProvider.cs b/framework/src/Volo.Abp.Ldap.Abstractions/Volo/Abp/Ldap/ILdapSettingProvider.cs
index efc109a762..c7320a36fa 100644
--- a/framework/src/Volo.Abp.Ldap.Abstractions/Volo/Abp/Ldap/ILdapSettingProvider.cs
+++ b/framework/src/Volo.Abp.Ldap.Abstractions/Volo/Abp/Ldap/ILdapSettingProvider.cs
@@ -4,15 +4,15 @@ namespace Volo.Abp.Ldap;
 
 public interface ILdapSettingProvider
 {
-    public Task<string> GetServerHostAsync();
+    public Task<string?> GetServerHostAsync();
 
     public Task<int> GetServerPortAsync();
 
-    public Task<string> GetBaseDcAsync();
+    public Task<string?> GetBaseDcAsync();
 
-    public Task<string> GetDomainAsync();
+    public Task<string?> GetDomainAsync();
 
-    public Task<string> GetUserNameAsync();
+    public Task<string?> GetUserNameAsync();
 
-    public Task<string> GetPasswordAsync();
+    public Task<string?> GetPasswordAsync();
 }
diff --git a/framework/src/Volo.Abp.Ldap/Volo.Abp.Ldap.csproj b/framework/src/Volo.Abp.Ldap/Volo.Abp.Ldap.csproj
index 951cbf3be2..aee7d78518 100644
--- a/framework/src/Volo.Abp.Ldap/Volo.Abp.Ldap.csproj
+++ b/framework/src/Volo.Abp.Ldap/Volo.Abp.Ldap.csproj
@@ -5,6 +5,8 @@
 
   <PropertyGroup>
     <TargetFrameworks>netstandard2.0;netstandard2.1;net7.0</TargetFrameworks>
+    <Nullable>enable</Nullable>
+    <WarningsAsErrors>Nullable</WarningsAsErrors>
     <AssemblyName>Volo.Abp.Ldap</AssemblyName>
     <PackageId>Volo.Abp.Ldap</PackageId>
     <AssetTargetFallback>$(AssetTargetFallback);portable-net45+win8+wp8+wpa81;</AssetTargetFallback>
diff --git a/framework/src/Volo.Abp.Ldap/Volo/Abp/Ldap/LdapSettingProvider.cs b/framework/src/Volo.Abp.Ldap/Volo/Abp/Ldap/LdapSettingProvider.cs
index ab36c1bf5f..cf43f11d43 100644
--- a/framework/src/Volo.Abp.Ldap/Volo/Abp/Ldap/LdapSettingProvider.cs
+++ b/framework/src/Volo.Abp.Ldap/Volo/Abp/Ldap/LdapSettingProvider.cs
@@ -14,7 +14,7 @@ public class LdapSettingProvider : ILdapSettingProvider, ITransientDependency
         SettingProvider = settingProvider;
     }
 
-    public async Task<string> GetServerHostAsync()
+    public async Task<string?> GetServerHostAsync()
     {
         return await SettingProvider.GetOrNullAsync(LdapSettingNames.ServerHost);
     }
@@ -24,22 +24,22 @@ public class LdapSettingProvider : ILdapSettingProvider, ITransientDependency
         return (await SettingProvider.GetOrNullAsync(LdapSettingNames.ServerPort))?.To<int>() ?? default;
     }
 
-    public async Task<string> GetBaseDcAsync()
+    public async Task<string?> GetBaseDcAsync()
     {
         return await SettingProvider.GetOrNullAsync(LdapSettingNames.BaseDc);
     }
 
-    public async Task<string> GetDomainAsync()
+    public async Task<string?> GetDomainAsync()
     {
         return await SettingProvider.GetOrNullAsync(LdapSettingNames.Domain);
     }
 
-    public async Task<string> GetUserNameAsync()
+    public async Task<string?> GetUserNameAsync()
     {
         return await SettingProvider.GetOrNullAsync(LdapSettingNames.UserName);
     }
 
-    public async Task<string> GetPasswordAsync()
+    public async Task<string?> GetPasswordAsync()
     {
         return await SettingProvider.GetOrNullAsync(LdapSettingNames.Password);
     }