diff --git a/backend/migrations/001_init.sql b/backend/migrations/001_init.sql
index 9f57b74..3f56509 100644
--- a/backend/migrations/001_init.sql
+++ b/backend/migrations/001_init.sql
@@ -104,7 +104,6 @@ ALTER TABLE audit_log
 ALTER TABLE audit_log
   ADD COLUMN IF NOT EXISTS ip_address TEXT;
 
--- details existed already, but make it safer for newer code
 ALTER TABLE audit_log
   ALTER COLUMN details SET DEFAULT '{}';
 
@@ -114,17 +113,41 @@ SET local_part = split_part(email_address, '@', 1)
 WHERE local_part IS NULL
   AND email_address LIKE '%@%';
 
--- Keep old and new usage timestamp columns in sync initially
-UPDATE mailboxes
-SET usage_scanned_at = last_usage_scan_at
-WHERE usage_scanned_at IS NULL
-  AND last_usage_scan_at IS NOT NULL;
+-- Keep old and new usage timestamp columns in sync initially.
+-- This must be guarded because older/newer MVP databases may not have last_usage_scan_at.
+DO $$
+BEGIN
+  IF EXISTS (
+    SELECT 1
+    FROM information_schema.columns
+    WHERE table_schema = 'public'
+      AND table_name = 'mailboxes'
+      AND column_name = 'last_usage_scan_at'
+  ) THEN
+    UPDATE mailboxes
+    SET usage_scanned_at = last_usage_scan_at
+    WHERE usage_scanned_at IS NULL
+      AND last_usage_scan_at IS NOT NULL;
+  END IF;
+END $$;
 
--- Backfill new audit target columns from old target column
-UPDATE audit_log
-SET target_id = target
-WHERE target_id IS NULL
-  AND target IS NOT NULL;
+-- Backfill new audit target columns from old target column.
+-- This must also be guarded because some installations may already use target_id only.
+DO $$
+BEGIN
+  IF EXISTS (
+    SELECT 1
+    FROM information_schema.columns
+    WHERE table_schema = 'public'
+      AND table_name = 'audit_log'
+      AND column_name = 'target'
+  ) THEN
+    UPDATE audit_log
+    SET target_id = target
+    WHERE target_id IS NULL
+      AND target IS NOT NULL;
+  END IF;
+END $$;
 
 UPDATE audit_log
 SET target_type = 'unknown'