diff --git a/pbs-datastore/src/datastore.rs b/pbs-datastore/src/datastore.rs
index d745be39..5af8a295 100644
--- a/pbs-datastore/src/datastore.rs
+++ b/pbs-datastore/src/datastore.rs
@@ -487,6 +487,7 @@ impl DataStore {
                         log::debug!("namespace {ns} already removed")
                     }
                     Err(nix::Error::Sys(nix::errno::Errno::ENOTEMPTY)) if !delete_groups => {
+                        removed_all_requested = false;
                         log::debug!("skip removal of non-empty namespace {ns}")
                     }
                     Err(err) => {
diff --git a/src/api2/admin/namespace.rs b/src/api2/admin/namespace.rs
index 1f524cb0..20db97d6 100644
--- a/src/api2/admin/namespace.rs
+++ b/src/api2/admin/namespace.rs
@@ -168,7 +168,11 @@ pub fn delete_namespace(
     let datastore = DataStore::lookup_datastore(&store, Some(Operation::Write))?;
 
     if !datastore.remove_namespace_recursive(&ns, delete_groups)? {
-        bail!("group only partially deleted due to protected snapshots");
+        if delete_groups {
+            bail!("group only partially deleted due to protected snapshots");
+        } else {
+            bail!("only partially deleted due to existing groups but `delete-groups` not true ");
+        }
     }
 
     Ok(Value::Null)