diff --git a/lib/charms/data_platform_libs/v0/data_interfaces.py b/lib/charms/data_platform_libs/v0/data_interfaces.py
index df59585d53..5d1691d9f1 100644
--- a/lib/charms/data_platform_libs/v0/data_interfaces.py
+++ b/lib/charms/data_platform_libs/v0/data_interfaces.py
@@ -320,7 +320,7 @@ def _on_topic_requested(self, event: TopicRequestedEvent):
 
 # Increment this PATCH version before using `charmcraft publish-lib` or reset
 # to 0 if you are raising the major API version
-LIBPATCH = 22
+LIBPATCH = 23
 
 PYDEPS = ["ops>=2.0.0"]
 
@@ -807,6 +807,9 @@ def _fetch_relation_data_without_secrets(
         This is used typically when the Provides side wants to read the Requires side's data,
         or when the Requires side may want to read its own data.
         """
+        if app not in relation.data or not relation.data[app]:
+            return {}
+
         if fields:
             return {k: relation.data[app][k] for k in fields if k in relation.data[app]}
         else:
@@ -830,6 +833,9 @@ def _fetch_relation_data_with_secrets(
         normal_fields = []
 
         if not fields:
+            if app not in relation.data or not relation.data[app]:
+                return {}
+
             all_fields = list(relation.data[app].keys())
             normal_fields = [field for field in all_fields if not self._is_secret_field(field)]
 
@@ -853,8 +859,11 @@ def _fetch_relation_data_with_secrets(
 
     def _update_relation_data_without_secrets(
         self, app: Application, relation: Relation, data: Dict[str, str]
-    ):
+    ) -> None:
         """Updating databag contents when no secrets are involved."""
+        if app not in relation.data or relation.data[app] is None:
+            return
+
         if any(self._is_secret_field(key) for key in data.keys()):
             raise SecretsIllegalUpdateError("Can't update secret {key}.")
 
@@ -865,8 +874,19 @@ def _delete_relation_data_without_secrets(
         self, app: Application, relation: Relation, fields: List[str]
     ) -> None:
         """Remove databag fields 'fields' from Relation."""
+        if app not in relation.data or not relation.data[app]:
+            return
+
         for field in fields:
-            relation.data[app].pop(field)
+            try:
+                relation.data[app].pop(field)
+            except KeyError:
+                logger.debug(
+                    "Non-existing field was attempted to be removed from the databag %s, %s",
+                    str(relation.id),
+                    str(field),
+                )
+                pass
 
     # Public interface methods
     # Handling Relation Fields seamlessly, regardless if in databag or a Juju Secret
@@ -880,9 +900,6 @@ def get_relation(self, relation_name, relation_id) -> Relation:
                 "Relation %s %s couldn't be retrieved", relation_name, relation_id
             )
 
-        if not relation.app:
-            raise DataInterfacesError("Relation's application missing")
-
         return relation
 
     def fetch_relation_data(
@@ -1089,7 +1106,10 @@ def _delete_relation_secret(
         # Remove secret from the relation if it's fully gone
         if not new_content:
             field = self._generate_secret_field_name(group)
-            relation.data[self.local_app].pop(field)
+            try:
+                relation.data[self.local_app].pop(field)
+            except KeyError:
+                pass
 
         # Return the content that was removed
         return True
diff --git a/lib/charms/postgresql_k8s/v0/postgresql.py b/lib/charms/postgresql_k8s/v0/postgresql.py
index debac9ae11..099047b01f 100644
--- a/lib/charms/postgresql_k8s/v0/postgresql.py
+++ b/lib/charms/postgresql_k8s/v0/postgresql.py
@@ -32,7 +32,7 @@
 
 # Increment this PATCH version before using `charmcraft publish-lib` or reset
 # to 0 if you are raising the major API version
-LIBPATCH = 18
+LIBPATCH = 19
 
 INVALID_EXTRA_USER_ROLE_BLOCKING_MESSAGE = "invalid role(s) for extra user roles"
 
@@ -514,7 +514,7 @@ def build_postgresql_parameters(
             )
         if profile == "production":
             # Use 25% of the available memory for shared_buffers.
-            # and the remaind as cache memory.
+            # and the remaining as cache memory.
             shared_buffers = int(available_memory * 0.25)
             effective_cache_size = int(available_memory - shared_buffers)
             parameters.setdefault("shared_buffers", f"{int(shared_buffers/10**6)}MB")
diff --git a/pyproject.toml b/pyproject.toml
index 2831db7a3b..d73786fc79 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -99,6 +99,9 @@ target-version = ["py38"]
 
 # Linting tools configuration
 [tool.ruff]
+# preview and explicit preview are enabled for CPY001
+preview = true
+explicit-preview-rules = true
 target-version = "py38"
 src = ["src", "."]
 line-length = 99