diff --git a/README.md b/README.md
index 62c8210..3c3363c 100644
--- a/README.md
+++ b/README.md
@@ -126,10 +126,10 @@ Then manually run the
 [release GitHub action](https://github.com/novonordisk-research/OptiHPLCHandler/actions/workflows/release.yml)
 by clicking `Run workflow`. Select what type of release it is by typing in `--patch`, `--minor`, or `--major` in `The type of release to perform`, and then click `Run workflow`.
 
-Fetch the new branch `release`. Make sure there isn't a `dist` folder in
-your project folder (or delete it), and run the commands
+Fetch the new branch `release`. Run the commands
 
 ```
+rm -r -fo dist
 py -m build
 py -m twine upload dist/*
 ```
diff --git a/pyproject.toml b/pyproject.toml
index 50f1343..801ebb2 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -1,6 +1,6 @@
 [project]
 name = "Opti_HPLC_Handler"
-version = "0.2.6"
+version = "0.2.7"
 description = "Simplified proxy API for interacting with the Waters Empower Web API."
 readme = "README.md"
 requires-python = ">=3.8"
@@ -85,7 +85,7 @@ pythonpath = [
 ]
 
 [tool.bumpver]
-current_version = "0.2.6"
+current_version = "0.2.7"
 version_pattern = "MAJOR.MINOR.PATCH"
 commit_message = "bump version {old_version} -> {new_version}"
 tag_message = "{new_version}"
diff --git a/src/OptiHPLCHandler/__init__.py b/src/OptiHPLCHandler/__init__.py
index d71e8f6..7afb0fe 100644
--- a/src/OptiHPLCHandler/__init__.py
+++ b/src/OptiHPLCHandler/__init__.py
@@ -2,6 +2,6 @@
 from .empower_api_core import EmpowerConnection
 from .empower_handler import EmpowerHandler
 
-__version__ = "0.2.6"
+__version__ = "0.2.7"
 
 __all__ = ["DataField", "EmpowerConnection", "EmpowerHandler", "HPLCSetup", "Sample"]
diff --git a/src/OptiHPLCHandler/empower_handler.py b/src/OptiHPLCHandler/empower_handler.py
index 1990d61..2f42807 100644
--- a/src/OptiHPLCHandler/empower_handler.py
+++ b/src/OptiHPLCHandler/empower_handler.py
@@ -144,9 +144,13 @@ def PostExperiment(
         endpoint = "project/methods/sample-set-method"
         if audit_trail_message:
             logger.debug("Adding audit trail message to endpoint")
-            endpoint += f"&auditTrailComment={audit_trail_message}"
+            endpoint += f"?auditTrailComment={audit_trail_message}"
         response = self.connection.post(endpoint=endpoint, body=sampleset_object)
         if response.status_code != 201:
+            if response.status_code == 404:
+                raise ValueError(
+                    "Could not post sample set method. Resource not found."
+                )
             raise ValueError(
                 f"Could not post sample set method. Response: {response.text}"
             )
diff --git a/tests/test_proxy_api.py b/tests/test_proxy_api.py
index 07d5760..45be83f 100644
--- a/tests/test_proxy_api.py
+++ b/tests/test_proxy_api.py
@@ -80,7 +80,7 @@ def test_empower_handler_post_sample_list(self, mock_requests):
         assert "test_sampleset_name" == mock_requests.method_calls[0][2]["json"]["name"]
         # Testing that the name is correct in the request
         assert (
-            "auditTrailComment=test_audit_trail_message"
+            "?auditTrailComment=test_audit_trail_message"
             in mock_requests.method_calls[0][1][0]
         )
         # Testing that the audit trail message is correct
@@ -135,6 +135,31 @@ def test_empower_handler_post_sample_list(self, mock_requests):
         assert all([dict_type == "Enumerator" for dict_type in dict_type_list])
         # Testing that all dictionary values are strings
 
+    @patch("OptiHPLCHandler.empower_api_core.requests")
+    def test_empower_handler_post_sample_list_error(self, mock_requests):
+        mock_response = MagicMock()
+        mock_response.json.return_value = {"results": "mock_results"}
+        mock_response.status_code = 404
+        mock_requests.post.return_value = mock_response
+        with self.assertRaises(ValueError) as context:
+            self.handler.PostExperiment(
+                sample_set_method_name="test_sampleset_name",
+                sample_list=[],
+                plate_list=[],
+                audit_trail_message="test_audit_trail_message",
+            )
+        assert "Resource not found" in context.exception.args[0]
+        mock_response.status_code = 400
+        mock_response.text = "mock_error_message"
+        with self.assertRaises(ValueError) as context:
+            self.handler.PostExperiment(
+                sample_set_method_name="test_sampleset_name",
+                sample_list=[],
+                plate_list=[],
+                audit_trail_message="test_audit_trail_message",
+            )
+        assert "Response: mock_error_message" in context.exception.args[0]
+
     def test_empower_handler_add_method(self):
         with self.assertRaises(NotImplementedError):
             self.handler.AddMethod(