diff --git a/cannamanage-frontend/Dockerfile b/cannamanage-frontend/Dockerfile
index 346b785..45039fe 100644
--- a/cannamanage-frontend/Dockerfile
+++ b/cannamanage-frontend/Dockerfile
@@ -20,6 +20,7 @@ ENV AUTH_SECRET=build-time-placeholder-secret-minimum-32-characters
 ENV NEXTAUTH_SECRET=build-time-placeholder-secret-minimum-32-characters
 ENV AUTH_TRUST_HOST=1
 ENV BACKEND_URL=http://localhost:8080
+ENV BASE_URL=http://localhost:3000
 RUN pnpm build
 
 FROM base AS runner
diff --git a/cannamanage-frontend/src/app/layout.tsx b/cannamanage-frontend/src/app/layout.tsx
index bf48909..39af928 100644
--- a/cannamanage-frontend/src/app/layout.tsx
+++ b/cannamanage-frontend/src/app/layout.tsx
@@ -22,7 +22,10 @@ export const metadata: Metadata = {
     default: "CannaManage",
   },
   description: "Cannabis club management platform — CannaManage",
-  metadataBase: new URL(process.env.BASE_URL as string),
+  // Guard against undefined BASE_URL: `new URL(undefined)` throws ERR_INVALID_URL
+  // during Next.js "Collecting page data" (root layout metadata is evaluated for
+  // every route). Falls back to localhost; real value injected at runtime via env.
+  metadataBase: new URL(process.env.BASE_URL ?? "http://localhost:3000"),
   manifest: "/manifest.json",
   themeColor: "#2ECC71",
   appleWebApp: {