1. Check your phone's internet connection
Nowadays WhatsApp Web can work independently for a while thanks to multi-device, but if your phone has been without an internet connection (neither wifi nor mobile data) for a long time, sync problems can appear. Check that your phone has a stable connection before moving on to the next steps.
2. Link again by scanning the QR code
If the session has gotten stuck, the fastest fix is usually to link the device again. On your phone, go to Settings → Linked devices → Link a device, and scan the QR code shown on your computer screen.
3. Update your computer's browser
WhatsApp Web needs a relatively recent browser version to work properly. Check for pending updates in Chrome, Edge or Firefox and restart the browser after installing them.
4. Check your phone's date and time
If your phone's date or time is set incorrectly, the secure verification of the session between the phone and the browser can fail. Turn on "Automatic date and time" in your phone's system settings.
5. Close old sessions from your phone
Having many devices linked at once can cause sync failures. Go to Settings → Linked devices on your phone and review the list: log out of any devices you no longer recognize or use.
- On your phone: Settings → Linked devices → select the device → Log out.
- Tip: do this too if you've used WhatsApp Web on a public or shared computer.
6. Clear your browser's cache or cookies
Sometimes the problem lies in the browser's own saved data for the web.whatsapp.com page. Go into your browser settings, find the privacy or site data section, and clear the cache and cookies just for that site. Then reload web.whatsapp.com and link again if it asks you to.