diff --git a/shopdb/core/api/shopdbbackups.py b/shopdb/core/api/shopdbbackups.py
index 5e2a325e..acac2125 100644
--- a/shopdb/core/api/shopdbbackups.py
+++ b/shopdb/core/api/shopdbbackups.py
@@ -340,13 +340,30 @@ def _known_plugin_revisions():
     if not manager:
         return {}
 
+    try:
+        from alembic.config import Config
+        from alembic.script import ScriptDirectory
+    except ImportError:
+        return {}
+
     known = {}
     for plugin_name in manager.registry.get_all():
         try:
-            revisions = manager.migration_manager.get_plugin_revisions(plugin_name)
+            migrations_dir = manager.migration_manager.get_migrations_dir(plugin_name)
+            if not migrations_dir:
+                continue
+
+            # Point alembic at this plugin's migrations directory
+            config = Config()
+            config.set_main_option('script_location', str(migrations_dir))
+            script = ScriptDirectory.from_config(config)
+
+            # Walk all revisions (heads and ancestors) for this plugin
+            revisions = {rev.revision for rev in script.walk_revisions()}
             if revisions:
-                known[plugin_name] = set(revisions)
+                known[plugin_name] = revisions
         except Exception:
+            # Skip plugins that fail to load or have malformed migrations
             continue
 
     return known