diff --git a/.changelogs/1.1.8/318_fix_conntrack_aware_migrations_api_pve8.yml b/.changelogs/1.1.8/318_fix_conntrack_aware_migrations_api_pve8.yml
new file mode 100644
index 0000000..6b438d3
--- /dev/null
+++ b/.changelogs/1.1.8/318_fix_conntrack_aware_migrations_api_pve8.yml
@@ -0,0 +1,2 @@
+fixed:
+  - Fix API errors when using conntrack aware migration with older PVE versions. (@gyptazy). [#318]
diff --git a/.changelogs/1.1.8/release_meta.yml b/.changelogs/1.1.8/release_meta.yml
new file mode 100644
index 0000000..c19765d
--- /dev/null
+++ b/.changelogs/1.1.8/release_meta.yml
@@ -0,0 +1 @@
+date: TBD
diff --git a/proxlb/models/balancing.py b/proxlb/models/balancing.py
index 9f641da..765d1b2 100644
--- a/proxlb/models/balancing.py
+++ b/proxlb/models/balancing.py
@@ -156,18 +156,17 @@ class Balancing:
         else:
             with_local_disks = 0
 
-        if proxlb_data["meta"]["balancing"].get("with_conntrack_state", True):
-            with_conntrack_state = 1
-        else:
-            with_conntrack_state = 0
-
         migration_options = {
             'target': guest_node_target,
             'online': online_migration,
             'with-local-disks': with_local_disks,
-            'with-conntrack-state': with_conntrack_state,
         }
 
+        # Conntrack state aware migrations are not supported in older
+        # PVE versions, so we should not add it by default.
+        if proxlb_data["meta"]["balancing"].get("with_conntrack_state", True):
+            migration_options['with-conntrack-state'] = 1
+
         try:
             logger.info(f"Balancing: Starting to migrate VM guest {guest_name} from {guest_node_current} to {guest_node_target}.")
             job_id = proxmox_api.nodes(guest_node_current).qemu(guest_id).migrate().post(**migration_options)