diff --git a/tests/orchestrator/activities/test_formatters.py b/tests/orchestrator/activities/test_formatters.py
index 92ba98c..b75cdfc 100644
--- a/tests/orchestrator/activities/test_formatters.py
+++ b/tests/orchestrator/activities/test_formatters.py
@@ -268,6 +268,70 @@ async def test_process_slots(mock_build_tag_config, mock_gather_read_tags, forma
     }
 
 
+@mark.asyncio
+@patch("orchestrator.activities.formatters.gather_read_tags",
+       return_value={
+           "1:test_tag_address": {
+               "server_id": "1",
+               "server_name": "test_server_name",
+               "tag_address": "test_tag_address",
+               "topics": ["raw_test_schedule"]
+           },
+           "2:test_tag_address2": {
+               "server_id": "2",
+               "server_name": "test_server_name2",
+               "tag_address": "test_tag_address2",
+               "topics": ["raw_test_schedule2"]
+           }
+       })
+@patch("orchestrator.activities.formatters.build_tag_config", side_effect=ValueError("test_error"))
+async def test_process_slots_exception(mock_build_tag_config, mock_gather_read_tags, formatters):
+    input_data = {
+        **metadata,
+        "opc_servers": [
+            {
+                "id": "1",
+                "server_name": "test_server_name",
+                "url": "test_url",
+                "uri": "test_uri",
+                "security_spec": {
+                    "test_name": "test_spec"
+                }
+            },
+            {
+                "id": "2",
+                "server_name": "test_server_name2",
+                "url": "test_url2",
+                "uri": "test_uri2"
+            }
+        ],
+        "active_ingestors": [
+            "test_active_ingestor1",
+            "test_active_ingestor2"
+        ],
+        "pipelines": "test_gather_read_tags"
+    }
+
+    await formatters.process_slots(input_data)
+
+    formatters.send_notification.assert_has_calls([
+        call(
+            metadata=metadata['metadata'],
+            notification_id="ORCHESTRATOR_BUILD_TAG_CONFIG_ERROR",
+            message="test_error",
+            block="orchestrator",
+            level=NotificationLevel.ERROR
+        ),
+        call(
+            metadata=metadata['metadata'],
+            notification_id="ORCHESTRATOR_BUILD_TAG_CONFIG_ERROR",
+            message="test_error",
+            block="orchestrator",
+            level=NotificationLevel.ERROR
+        )
+    ])
+
+
 @mark.asyncio
 async def test_format_schedule_config(formatters):
     input_data = {
diff --git a/tests/orchestrator/utils/test_orchestrator_functions.py b/tests/orchestrator/utils/test_orchestrator_functions.py
index 09c541d..e0b08a9 100644
--- a/tests/orchestrator/utils/test_orchestrator_functions.py
+++ b/tests/orchestrator/utils/test_orchestrator_functions.py
@@ -342,3 +342,16 @@ def test_build_tag_config():
         }
     }
     assert result == expected
+
+
+def test_build_tag_config_no_server_id():
+    tag = {
+        "server_id": "1",
+        "tag_address": "test_tag_address"
+    }
+    opc_servers = {}
+
+    try:
+        build_tag_config(tag, {}, opc_servers, 1)
+    except ValueError as e:
+        assert str(e) == "Server 1 not found in opc_servers"