diff --git a/aiidalab_widgets_base/computational_resources.py b/aiidalab_widgets_base/computational_resources.py
index d4837f575..e1c67745e 100644
--- a/aiidalab_widgets_base/computational_resources.py
+++ b/aiidalab_widgets_base/computational_resources.py
@@ -61,7 +61,16 @@ def __init__(self, description="Select code:", path_to_root="../", **kwargs):
             value=None,
             style={"description_width": "initial"},
         )
-        traitlets.link((self, "codes"), (self.code_select_dropdown, "options"))
+        traitlets.directional_link(
+            (self, "codes"),
+            (self.code_select_dropdown, "options"),
+            transform=lambda x: [(key, x[key]) for key in x],
+        )
+        traitlets.directional_link(
+            (self.code_select_dropdown, "options"),
+            (self, "codes"),
+            transform=lambda x: {c[0]: c[1] for c in x},
+        )
         traitlets.link((self.code_select_dropdown, "value"), (self, "value"))
 
         self.observe(
@@ -161,8 +170,8 @@ def _get_codes(self):
 
         user = orm.User.collection.get_default()
 
-        return {
-            self._full_code_label(c[0]): c[0].uuid
+        return [
+            (self._full_code_label(c[0]), c[0].uuid)
             for c in orm.QueryBuilder()
             .append(
                 orm.Code,
@@ -172,7 +181,7 @@ def _get_codes(self):
             if c[0].computer.is_user_configured(user)
             and (self.allow_hidden_codes or not c[0].is_hidden)
             and (self.allow_disabled_computers or c[0].computer.is_user_enabled(user))
-        }
+        ]
 
     @staticmethod
     def _full_code_label(code):
@@ -335,7 +344,6 @@ def __init__(self, **kwargs):
         self._inp_private_key = ipw.FileUpload(
             accept="",
             layout=LAYOUT,
-            style=STYLE,
             description="Private key",
             multiple=False,
         )
@@ -1187,14 +1195,22 @@ def __init__(self, description="Select computer:", path_to_root="../", **kwargs)
 
         self.output = ipw.HTML()
         self._dropdown = ipw.Dropdown(
-            options={},
             value=None,
             description=description,
             style=STYLE,
             layout=LAYOUT,
             disabled=True,
         )
-        traitlets.link((self, "computers"), (self._dropdown, "options"))
+        traitlets.directional_link(
+            (self, "computers"),
+            (self._dropdown, "options"),
+            transform=lambda x: [(key, x[key]) for key in x],
+        )
+        traitlets.directional_link(
+            (self._dropdown, "options"),
+            (self, "computers"),
+            transform=lambda x: {c[0]: c[1] for c in x},
+        )
         traitlets.link((self._dropdown, "value"), (self, "value"))
 
         self.observe(self.refresh, names="allow_select_disabled")
@@ -1210,18 +1226,18 @@ def __init__(self, description="Select computer:", path_to_root="../", **kwargs)
         self.refresh()
         super().__init__(children=children, **kwargs)
 
-    def _get_computers(self):
+    def _get_computers(self) -> list:
         """Get the list of available computers."""
 
         # Getting the current user.
         user = orm.User.collection.get_default()
 
-        return {
-            c[0].label: c[0].uuid
+        return [
+            (c[0].label, c[0].uuid)
             for c in orm.QueryBuilder().append(orm.Computer).all()
             if c[0].is_user_configured(user)
             and (self.allow_select_disabled or c[0].is_user_enabled(user))
-        }
+        ]
 
     def refresh(self, _=None):
         """Refresh the list of configured computers."""
diff --git a/aiidalab_widgets_base/databases.py b/aiidalab_widgets_base/databases.py
index 742e621f6..2302e737f 100644
--- a/aiidalab_widgets_base/databases.py
+++ b/aiidalab_widgets_base/databases.py
@@ -223,7 +223,7 @@ def __init__(self, **kwargs):
         self.inp_computer = ipw.Dropdown(
             options=[],
             description="Computer:",
-            disable=False,
+            disabled=False,
         )
         self.inp_computer.observe(self._computer_changed, names=["value", "options"])
 
@@ -231,7 +231,7 @@ def __init__(self, **kwargs):
         self.inp_code = ipw.Dropdown(
             options=[],
             description="Code:",
-            disable=False,
+            disabled=False,
         )
         self.inp_code.observe(self._code_changed, names=["value", "options"])
 
diff --git a/tests/test_computational_resources.py b/tests/test_computational_resources.py
index 9ca1b7655..c496302c9 100644
--- a/tests/test_computational_resources.py
+++ b/tests/test_computational_resources.py
@@ -5,15 +5,15 @@
 
 
 @pytest.mark.usefixtures("aiida_profile_clean")
-def test_computaional_resources_widget(aiida_local_code_bash):
+def test_computational_resources_widget(aiida_local_code_bash):
     """Test the ComputationalResourcesWidget."""
     widget = computational_resources.ComputationalResourcesWidget(
         default_calc_job_plugin="bash"
     )
 
     # Get the list of currently installed codes.
-    codes_dict = widget._get_codes()
-    assert "bash@localhost" in codes_dict
+    codes = widget._get_codes()
+    assert "bash@localhost" == codes[0][0]
 
 
 @pytest.mark.usefixtures("aiida_profile_clean")