diff --git a/apiserver/plane/api/serializers/project.py b/apiserver/plane/api/serializers/project.py
index 34afca72b..cdc9adf36 100644
--- a/apiserver/plane/api/serializers/project.py
+++ b/apiserver/plane/api/serializers/project.py
@@ -29,12 +29,18 @@ class ProjectSerializer(BaseSerializer):
         if identifier == "":
             raise serializers.ValidationError(detail="Project Identifier is required")
 
-        if ProjectIdentifier.objects.filter(name=identifier).exists():
+        if ProjectIdentifier.objects.filter(
+            name=identifier, workspace_id=self.context["workspace_id"]
+        ).exists():
             raise serializers.ValidationError(detail="Project Identifier is taken")
         project = Project.objects.create(
             **validated_data, workspace_id=self.context["workspace_id"]
         )
-        _ = ProjectIdentifier.objects.create(name=project.identifier, project=project)
+        _ = ProjectIdentifier.objects.create(
+            name=project.identifier,
+            project=project,
+            workspace_id=self.context["workspace_id"],
+        )
         return project
 
     def update(self, instance, validated_data):
@@ -47,7 +53,9 @@ class ProjectSerializer(BaseSerializer):
             return project
 
         # If no Project Identifier is found create it
-        project_identifier = ProjectIdentifier.objects.filter(name=identifier).first()
+        project_identifier = ProjectIdentifier.objects.filter(
+            name=identifier, workspace_id=instance.workspace_id
+        ).first()
 
         if project_identifier is None:
             project = super().update(instance, validated_data)
@@ -61,9 +69,7 @@ class ProjectSerializer(BaseSerializer):
             return project
 
         # If not same fail update
-        raise serializers.ValidationError(
-            detail="Project Identifier is already taken"
-        )
+        raise serializers.ValidationError(detail="Project Identifier is already taken")
 
 
 class ProjectDetailSerializer(BaseSerializer):
diff --git a/apiserver/plane/api/views/project.py b/apiserver/plane/api/views/project.py
index 1dc00e404..0685cebe4 100644
--- a/apiserver/plane/api/views/project.py
+++ b/apiserver/plane/api/views/project.py
@@ -144,9 +144,13 @@ class ProjectViewSet(BaseViewSet):
         except IntegrityError as e:
             if "already exists" in str(e):
                 return Response(
-                    {"name": "The project name is already taken"},
+                    {"identifier": "The project identifier is already taken"},
                     status=status.HTTP_410_GONE,
                 )
+        except Workspace.DoesNotExist as e:
+            return Response(
+                {"error": "Workspace does not exist"}, status=status.HTTP_404_NOT_FOUND
+            )
         except serializers.ValidationError as e:
             return Response(
                 {"identifier": "The project identifier is already taken"},
@@ -183,6 +187,10 @@ class ProjectViewSet(BaseViewSet):
                     {"name": "The project name is already taken"},
                     status=status.HTTP_410_GONE,
                 )
+        except (Project.DoesNotExist or Workspace.DoesNotExist) as e:
+            return Response(
+                {"error": "Project does not exist"}, status=status.HTTP_404_NOT_FOUND
+            )
         except serializers.ValidationError as e:
             return Response(
                 {"identifier": "The project identifier is already taken"},
@@ -498,9 +506,9 @@ class ProjectIdentifierEndpoint(BaseAPIView):
                     {"error": "Name is required"}, status=status.HTTP_400_BAD_REQUEST
                 )
 
-            exists = ProjectIdentifier.objects.filter(name=name).values(
-                "id", "name", "project"
-            )
+            exists = ProjectIdentifier.objects.filter(
+                name=name, workspace__slug=slug
+            ).values("id", "name", "project")
 
             return Response(
                 {"exists": len(exists), "identifiers": exists},
@@ -523,13 +531,13 @@ class ProjectIdentifierEndpoint(BaseAPIView):
                     {"error": "Name is required"}, status=status.HTTP_400_BAD_REQUEST
                 )
 
-            if Project.objects.filter(identifier=name).exists():
+            if Project.objects.filter(identifier=name, workspace__slug=slug).exists():
                 return Response(
                     {"error": "Cannot delete an identifier of an existing project"},
                     status=status.HTTP_400_BAD_REQUEST,
                 )
 
-            ProjectIdentifier.objects.filter(name=name).delete()
+            ProjectIdentifier.objects.filter(name=name, workspace__slug=slug).delete()
 
             return Response(
                 status=status.HTTP_204_NO_CONTENT,
diff --git a/apiserver/plane/db/models/project.py b/apiserver/plane/db/models/project.py
index 2e253ea1b..02fea2c7c 100644
--- a/apiserver/plane/db/models/project.py
+++ b/apiserver/plane/db/models/project.py
@@ -35,7 +35,8 @@ class Project(BaseModel):
         "db.WorkSpace", on_delete=models.CASCADE, related_name="workspace_project"
     )
     identifier = models.CharField(
-        max_length=5, verbose_name="Project Identifier", null=True, blank=True
+        max_length=5,
+        verbose_name="Project Identifier",
     )
     slug = models.SlugField(max_length=100, blank=True)
     default_assignee = models.ForeignKey(
@@ -58,7 +59,7 @@ class Project(BaseModel):
         return f"{self.name} <{self.workspace.name}>"
 
     class Meta:
-        unique_together = ["name", "workspace"]
+        unique_together = ["identifier", "workspace"]
         verbose_name = "Project"
         verbose_name_plural = "Projects"
         db_table = "project"
@@ -131,12 +132,17 @@ class ProjectMember(ProjectBaseModel):
 
 
 class ProjectIdentifier(AuditModel):
+
+    workspace = models.ForeignKey(
+        "db.Workspace", models.CASCADE, related_name="project_identifiers", null=True
+    )
     project = models.OneToOneField(
         Project, on_delete=models.CASCADE, related_name="project_identifier"
     )
     name = models.CharField(max_length=10)
 
     class Meta:
+        unique_together = ["name", "workspace"]
         verbose_name = "Project Identifier"
         verbose_name_plural = "Project Identifiers"
         db_table = "project_identifier"