https://github.com/sunkaixuan/SqlSugar/issues/149

Src/Asp.Net/SqlSugar/Abstract/AdoProvider/AdoProvider.cs

@@ -109,6 +109,8 @@ namespace SqlSugar
             this.Connection = null;
 
             if (this.IsMasterSlaveSeparation)
+            {
+                if (this.SlaveConnections != null)
                 {
                     foreach (var slaveConnection in this.SlaveConnections)
                     {
@@ -119,6 +121,7 @@ namespace SqlSugar
                     }
                 }
             }
+        }
         public virtual void CheckConnection()
         {
             if (this.Connection.State != ConnectionState.Open)