diff --git a/hapi-fhir-base/src/main/resources/ca/uhn/fhir/i18n/hapi-messages.properties b/hapi-fhir-base/src/main/resources/ca/uhn/fhir/i18n/hapi-messages.properties
index 5c8dbaab662..5cbae62faa5 100644
--- a/hapi-fhir-base/src/main/resources/ca/uhn/fhir/i18n/hapi-messages.properties
+++ b/hapi-fhir-base/src/main/resources/ca/uhn/fhir/i18n/hapi-messages.properties
@@ -188,6 +188,7 @@ ca.uhn.fhir.jpa.dao.index.IdHelperService.nonUniqueForcedId=Non-unique ID specif
 
 ca.uhn.fhir.jpa.partition.PartitionLookupSvcImpl.noIdSupplied=No Partition ID supplied
 ca.uhn.fhir.jpa.partition.PartitionLookupSvcImpl.missingPartitionIdOrName=Partition must have an ID and a Name
+ca.uhn.fhir.jpa.partition.PartitionLookupSvcImpl.duplicatePartitionId=Partition ID already exists
 ca.uhn.fhir.jpa.partition.PartitionLookupSvcImpl.unknownPartitionId=No partition exists with ID {0}
 ca.uhn.fhir.jpa.partition.PartitionLookupSvcImpl.invalidName=Partition name "{0}" is not valid
 ca.uhn.fhir.jpa.partition.PartitionLookupSvcImpl.cantCreateDuplicatePartitionName=Partition name "{0}" is already defined
diff --git a/hapi-fhir-docs/src/main/resources/ca/uhn/hapi/fhir/changelog/6_8_0/5011-partitioning-can-create-more-than-one-partition-with-same-id.yaml b/hapi-fhir-docs/src/main/resources/ca/uhn/hapi/fhir/changelog/6_8_0/5011-partitioning-can-create-more-than-one-partition-with-same-id.yaml
new file mode 100644
index 00000000000..b685ee04221
--- /dev/null
+++ b/hapi-fhir-docs/src/main/resources/ca/uhn/hapi/fhir/changelog/6_8_0/5011-partitioning-can-create-more-than-one-partition-with-same-id.yaml
@@ -0,0 +1,5 @@
+---
+type: fix
+issue: 5011
+title: "Previously, if a partition was created with an ID that was already in use, it would overwrite the partition that 
+ was using that ID. Now attempting to overwrite will return a 400"
diff --git a/hapi-fhir-jpaserver-base/src/main/java/ca/uhn/fhir/jpa/partition/PartitionLookupSvcImpl.java b/hapi-fhir-jpaserver-base/src/main/java/ca/uhn/fhir/jpa/partition/PartitionLookupSvcImpl.java
index 679e3ac201a..c924fa1f12e 100644
--- a/hapi-fhir-jpaserver-base/src/main/java/ca/uhn/fhir/jpa/partition/PartitionLookupSvcImpl.java
+++ b/hapi-fhir-jpaserver-base/src/main/java/ca/uhn/fhir/jpa/partition/PartitionLookupSvcImpl.java
@@ -51,6 +51,7 @@ import org.springframework.transaction.support.TransactionTemplate;
 import javax.annotation.Nonnull;
 import javax.annotation.PostConstruct;
 import java.util.List;
+import java.util.ListIterator;
 import java.util.Optional;
 import java.util.concurrent.ThreadLocalRandom;
 import java.util.concurrent.TimeUnit;
@@ -141,7 +142,7 @@ public class PartitionLookupSvcImpl implements IPartitionLookupSvc {
 		validateNotInUnnamedPartitionMode();
 		validateHaveValidPartitionIdAndName(thePartition);
 		validatePartitionNameDoesntAlreadyExist(thePartition.getName());
-
+		validIdUponCreation(thePartition);
 		ourLog.info("Creating new partition with ID {} and Name {}", thePartition.getId(), thePartition.getName());
 
 		PartitionEntity retVal = myPartitionDao.save(thePartition);
@@ -212,6 +213,13 @@ public class PartitionLookupSvcImpl implements IPartitionLookupSvc {
 		}
 	}
 
+	private void validIdUponCreation(PartitionEntity thePartition){
+		if (myPartitionDao.findById(thePartition.getId()).isPresent()) {
+			String msg = myFhirCtx.getLocalizer().getMessageSanitized(PartitionLookupSvcImpl.class, "duplicatePartitionId");
+			throw new InvalidRequestException(Msg.code(2366) + msg);
+		}
+	}
+
 	private void validateHaveValidPartitionIdAndName(PartitionEntity thePartition) {
 		if (thePartition.getId() == null || isBlank(thePartition.getName())) {
 			String msg = myFhirCtx.getLocalizer().getMessage(PartitionLookupSvcImpl.class, "missingPartitionIdOrName");
@@ -227,7 +235,6 @@ public class PartitionLookupSvcImpl implements IPartitionLookupSvc {
 			String msg = myFhirCtx.getLocalizer().getMessageSanitized(PartitionLookupSvcImpl.class, "invalidName", thePartition.getName());
 			throw new InvalidRequestException(Msg.code(1312) + msg);
 		}
-
 	}
 
 	private void validateNotInUnnamedPartitionMode() {
diff --git a/hapi-fhir-jpaserver-test-r4/src/test/java/ca/uhn/fhir/jpa/partition/PartitionSettingsSvcImplTest.java b/hapi-fhir-jpaserver-test-r4/src/test/java/ca/uhn/fhir/jpa/partition/PartitionSettingsSvcImplTest.java
index 62cca49702c..71f81e8982e 100644
--- a/hapi-fhir-jpaserver-test-r4/src/test/java/ca/uhn/fhir/jpa/partition/PartitionSettingsSvcImplTest.java
+++ b/hapi-fhir-jpaserver-test-r4/src/test/java/ca/uhn/fhir/jpa/partition/PartitionSettingsSvcImplTest.java
@@ -103,6 +103,27 @@ public class PartitionSettingsSvcImplTest extends BaseJpaR4Test {
 		}
 	}
 
+	@Test
+	public void testCreatePartition_whenPartitionIdAlreadyExists_operationNotAllowed(){
+		try {
+			PartitionEntity partition = new PartitionEntity();
+			partition.setId(123);
+			partition.setName("NAME123");
+			partition.setDescription("A description");
+			myPartitionConfigSvc.createPartition(partition, null);
+
+			partition = new PartitionEntity();
+			partition.setId(123);
+			partition.setName("NAME111");
+			partition.setDescription("A description");
+			myPartitionConfigSvc.createPartition(partition, null);
+		}
+
+		catch (InvalidRequestException e) {
+			assertEquals( Msg.code(2366) + "Partition ID already exists", e.getMessage());
+		}
+	}
+
 	@Test
 	public void testUpdatePartition_TryToRenameDefault() {
 		PartitionEntity partition = new PartitionEntity();