npgsql
diff --git a/Collapse file
‎src/Npgsql/NpgsqlCommand.cs‎
Copy file name to clipboardExpand all lines: src/Npgsql/NpgsqlCommand.cs
+18-5Lines changed: 18 additions & 5 deletions b/Collapse file
‎src/Npgsql/NpgsqlCommand.cs‎
Copy file name to clipboardExpand all lines: src/Npgsql/NpgsqlCommand.cs
+18-5Lines changed: 18 additions & 5 deletions
diff --git a/Collapse file
‎test/Npgsql.Tests/CommandTests.cs‎
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+14Lines changed: 14 additions & 0 deletions b/Collapse file
‎test/Npgsql.Tests/CommandTests.cs‎
Copy file name to clipboardExpand all lines: test/Npgsql.Tests/CommandTests.cs
+14Lines changed: 14 additions & 0 deletions
@@ -183,8 +183,18 @@ public override string CommandText
         {
             Debug.Assert(WrappingBatch is null);
 
-            if (State != CommandState.Idle)
-                ThrowHelper.ThrowInvalidOperationException("An open data reader exists for this command.");
+            switch (State)
+            {
+                case CommandState.Idle:
+                    break;
+                case CommandState.Disposed:
+                    ThrowHelper.ThrowObjectDisposedException(typeof(NpgsqlCommand).FullName);
+                    break;
+                case CommandState.InProgress:
+                default:
+                    ThrowHelper.ThrowInvalidOperationException("An open data reader exists for this command.");
+                    break;
+            }
 
             _commandText = value ?? string.Empty;
 
@@ -252,9 +262,12 @@ protected override DbConnection? DbConnection
             if (InternalConnection == value)
                 return;
 
-            InternalConnection = State == CommandState.Idle
-                ? (NpgsqlConnection?)value
-                : throw new InvalidOperationException("An open data reader exists for this command.");
+            InternalConnection = State switch
+            {
+                CommandState.Idle => (NpgsqlConnection?)value,
+                CommandState.Disposed => throw new ObjectDisposedException(typeof(NpgsqlCommand).FullName),
+                _ => throw new InvalidOperationException("An open data reader exists for this command."),
+            };
 
             Transaction = null;
         }
 
@@ -1694,4 +1694,18 @@ public async Task Completed_transaction_throws([Values] bool commit)
 
         Assert.Throws<InvalidOperationException>(() => cmd.Transaction = tx);
     }
+
+    [Test, Description("Writing to properties of a disposed command raises ObjectDisposedException.")]
+    public async Task Disposed_command_throws_on_assignment()
+    {
+        await using var conn = await OpenConnectionAsync();
+        var command = new NpgsqlCommand("SELECT 1");
+        command.Dispose();
+
+        Assert.Throws<ObjectDisposedException>(() => command.Connection = conn);
+        Assert.Throws<ObjectDisposedException>(() => command.CommandText = "SELECT 2");
+
+        Assert.That(command.Connection, Is.Null);
+        Assert.That(command.CommandText, Is.EqualTo("SELECT 1"));
+    }
 }