diff --git a/modules/docs/src/Volo.Docs.Web/Pages/Documents/Project/Index.cshtml.cs b/modules/docs/src/Volo.Docs.Web/Pages/Documents/Project/Index.cshtml.cs
index c68d25d1e89..b640e058832 100644
--- a/modules/docs/src/Volo.Docs.Web/Pages/Documents/Project/Index.cshtml.cs
+++ b/modules/docs/src/Volo.Docs.Web/Pages/Documents/Project/Index.cshtml.cs
@@ -369,9 +369,9 @@ private string RemoveVersionPrefix(string version)
                 return version;
             }
 
-            var prefix = Project.ExtraProperties["VersionBranchPrefix"].ToString();
+            var prefix = Project.ExtraProperties["VersionBranchPrefix"]?.ToString();
 
-            if (string.IsNullOrWhiteSpace(version) || !version.StartsWith(prefix) || version.Length <= prefix.Length)
+            if (string.IsNullOrWhiteSpace(version) || string.IsNullOrWhiteSpace(prefix) || !version.StartsWith(prefix) || version.Length <= prefix.Length)
             {
                 return version;
             }