diff --git a/Projects/UOContent.Tests/Tests/Engines/Spawners/Json/AllSpawnFilesLoadTests.cs b/Projects/UOContent.Tests/Tests/Engines/Spawners/Json/AllSpawnFilesLoadTests.cs
new file mode 100644
index 000000000..9eb9e1909
--- /dev/null
+++ b/Projects/UOContent.Tests/Tests/Engines/Spawners/Json/AllSpawnFilesLoadTests.cs
@@ -0,0 +1,72 @@
+// Regression test: verifies that EVERY migrated spawn file deserializes and builds spawners.
+// This catches any migration defects where a spawn file is syntactically correct JSON
+// but fails to build spawners via DTO.ToSpawner(). Any failure names the offending file
+// and is a real migration defect, not a test weakness.
+
+using System;
+using System.Collections.Generic;
+using System.IO;
+using System.Text.Json;
+using Server;
+using Server.Engines.Spawners;
+using Xunit;
+
+namespace UOContent.Tests.Engines.Spawners.Json;
+
+[Collection("Sequential UOContent Tests")]
+public class AllSpawnFilesLoadTests
+{
+    [Fact]
+    public void EverySpawnFile_DeserializesAndBuildsSpawners()
+    {
+        var root = Path.Combine(Core.BaseDirectory, "Data", "Spawns");
+        if (!Directory.Exists(root))
+        {
+            return; // distribution data not present in this checkout
+        }
+
+        var failures = new List<string>();
+        var fileCount = 0;
+        var spawnerCount = 0;
+
+        foreach (var file in Directory.EnumerateFiles(root, "*.json", SearchOption.AllDirectories))
+        {
+            fileCount++;
+            try
+            {
+                var dtos = JsonSerializer.Deserialize<List<SpawnerDto>>(
+                    File.ReadAllText(file), SpawnerJsonSerializer.Options);
+
+                if (dtos != null)
+                {
+                    foreach (var dto in dtos)
+                    {
+                        try
+                        {
+                            var spawner = dto.ToSpawner();
+                            spawnerCount++;
+                            spawner?.Delete();
+                        }
+                        catch (Exception ex)
+                        {
+                            failures.Add($"{file}: ToSpawner failed: {ex.Message}");
+                        }
+                    }
+                }
+            }
+            catch (JsonException ex)
+            {
+                failures.Add($"{file}: JSON deserialization failed: {ex.Message}");
+            }
+            catch (Exception ex)
+            {
+                failures.Add($"{file}: {ex.GetType().Name}: {ex.Message}");
+            }
+        }
+
+        Assert.True(
+            failures.Count == 0,
+            $"Loaded {fileCount} files, built {spawnerCount} spawners. Failures:\n{string.Join("\n", failures)}"
+        );
+    }
+}