diff --git a/AsbCloudInfrastructure/Services/Cache/CacheTable.cs b/AsbCloudInfrastructure/Services/Cache/CacheTable.cs
index db0aee2e..445fb8cc 100644
--- a/AsbCloudInfrastructure/Services/Cache/CacheTable.cs
+++ b/AsbCloudInfrastructure/Services/Cache/CacheTable.cs
@@ -13,6 +13,7 @@ namespace AsbCloudInfrastructure.Services.Cache
         private (DateTime refreshDate, IEnumerable<object> entities) data;
         private readonly List<TEntity> cached;
         private readonly DbSet<TEntity> dbSet;
+        private readonly SemaphoreSlim semaphore = new SemaphoreSlim(1, 1);
 
         internal CacheTable(DbContext context, (DateTime refreshDate, IEnumerable<object> entities) data)
         {
@@ -27,7 +28,10 @@ namespace AsbCloudInfrastructure.Services.Cache
         public int Refresh()
         {
             if (cached.Any())
+            {
+                semaphore.Wait();
                 cached.Clear();
+            }
             var dbEntities = context.Set<TEntity>().AsNoTracking().ToList();
             cached.AddRange(dbEntities);
             data.refreshDate = DateTime.Now;
@@ -37,7 +41,10 @@ namespace AsbCloudInfrastructure.Services.Cache
         public async Task<int> RefreshAsync(CancellationToken token = default)
         {
             if (cached.Any())
-                cached.Clear();
+            {
+                await semaphore.WaitAsync(token).ConfigureAwait(true);
+                cached.Clear(); 
+            }
             var dbEntities = await context.Set<TEntity>().AsNoTracking().ToListAsync(token).ConfigureAwait(false);
             cached.AddRange(dbEntities);
             data.refreshDate = DateTime.Now;