diff --git a/Dockerfile b/Dockerfile
index a7091e356..4249f84ba 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -88,7 +88,8 @@ WORKDIR /app
 COPY package*.json ./
 
 # Install production dependencies only
-RUN npm ci --omit=dev && npm cache clean --force
+COPY scripts/patch-wwebjs-lid-last-received-key.js ./scripts/patch-wwebjs-lid-last-received-key.js
+RUN npm ci --omit=dev && node scripts/patch-wwebjs-lid-last-received-key.js && npm cache clean --force
 
 # amd64: download Chrome for Testing via Puppeteer and symlink it.
 # arm64: use Debian's chromium installed above (CfT has no linux-arm64 build).
@@ -114,7 +115,7 @@ COPY --from=builder /app/dashboard/dist ./dashboard/dist
 
 # Create data directories with correct ownership
 RUN mkdir -p ./data/sessions ./data/media && \
-    chown -R openwa:openwa /app
+    chown -R openwa:openwa ./data
 
 # The non-root openwa user has no home of its own (`useradd -r`, no -m). Chromium resolves the home
 # dir from the passwd entry via glib's getpwuid() — it IGNORES $HOME — so it tries to read/write
diff --git a/scripts/patch-wwebjs-lid-last-received-key.js b/scripts/patch-wwebjs-lid-last-received-key.js
new file mode 100644
index 000000000..8ba7b0a22
--- /dev/null
+++ b/scripts/patch-wwebjs-lid-last-received-key.js
@@ -0,0 +1,57 @@
+const fs = require('fs');
+const path = require('path');
+
+const DEFAULT_TARGET = path.join(
+  __dirname,
+  '..',
+  'node_modules',
+  'whatsapp-web.js',
+  'src',
+  'util',
+  'Injected',
+  'Utils.js',
+);
+
+const OLD_BLOCK = `            const lastMessage = chat.lastReceivedKey
+                ? window
+                      .require('WAWebCollections')
+                      .Msg.get(chat.lastReceivedKey._serialized) ||
+                  (
+                      await window
+                          .require('WAWebCollections')
+                          .Msg.getMessagesById([
+                              chat.lastReceivedKey._serialized,
+                          ])
+                  )?.messages?.[0]
+                : null;`;
+
+const NEW_BLOCK = `            const lastReceivedKey = chat.lastReceivedKey?._serialized || chat.lastReceivedKey?.toString?.();
+            const lastMessage = lastReceivedKey
+                ? window
+                      .require('WAWebCollections')
+                      .Msg.get(lastReceivedKey) ||
+                  (
+                      await window
+                          .require('WAWebCollections')
+                          .Msg.getMessagesById([
+                              lastReceivedKey,
+                          ])
+                  )?.messages?.[0]
+                : null;`;
+
+function applyPatch(target = DEFAULT_TARGET) {
+  const source = fs.readFileSync(target, 'utf8');
+  if (source.includes(NEW_BLOCK)) return 'already-patched';
+  if (!source.includes(OLD_BLOCK)) {
+    throw new Error(`Unsupported whatsapp-web.js Utils.js shape: ${target}`);
+  }
+  fs.writeFileSync(target, source.replace(OLD_BLOCK, NEW_BLOCK));
+  return 'patched';
+}
+
+if (require.main === module) {
+  const result = applyPatch(process.argv[2] || DEFAULT_TARGET);
+  console.log(`patch-wwebjs-lid-last-received-key: ${result}`);
+}
+
+module.exports = { applyPatch };
diff --git a/src/engine/adapters/wwebjs-patch.spec.ts b/src/engine/adapters/wwebjs-patch.spec.ts
new file mode 100644
index 000000000..2b291dd70
--- /dev/null
+++ b/src/engine/adapters/wwebjs-patch.spec.ts
@@ -0,0 +1,34 @@
+import * as fs from 'fs';
+import * as os from 'os';
+import * as path from 'path';
+
+describe('patch-wwebjs-lid-last-received-key', () => {
+  it('adds a string fallback for WhatsApp MsgKey objects without _serialized', () => {
+    // eslint-disable-next-line @typescript-eslint/no-var-requires
+    const { applyPatch } = require('../../../scripts/patch-wwebjs-lid-last-received-key');
+    const dir = fs.mkdtempSync(path.join(os.tmpdir(), 'wwebjs-patch-'));
+    const target = path.join(dir, 'Utils.js');
+    fs.writeFileSync(
+      target,
+      `            const lastMessage = chat.lastReceivedKey
+                ? window
+                      .require('WAWebCollections')
+                      .Msg.get(chat.lastReceivedKey._serialized) ||
+                  (
+                      await window
+                          .require('WAWebCollections')
+                          .Msg.getMessagesById([
+                              chat.lastReceivedKey._serialized,
+                          ])
+                  )?.messages?.[0]
+                : null;`,
+    );
+
+    expect(applyPatch(target)).toBe('patched');
+    const patched = fs.readFileSync(target, 'utf8');
+
+    expect(patched).toContain('chat.lastReceivedKey?._serialized || chat.lastReceivedKey?.toString?.()');
+    expect(patched).toContain('Msg.get(lastReceivedKey)');
+    expect(patched).toContain('Msg.getMessagesById([\n                              lastReceivedKey,');
+  });
+});