hello cesar colonia, sorry to head this problem, '''follow the steps and instruction fix the problem:''' firstly clear cookies and cache in your browser firefox, * Click the menu button. and select Options. Preferences. * Select the Privacy & Security panel and go to the Cookies and Site Data section. * Click the Clear Data… button. The Clear Data dialog will appear. ... * Click Clear. for more information: [[https://support.mozilla.org/en-US/kb/clear-cookies-and-site-data-firefox]] '''then Goto safe mode:''' ctrl+shift+N at a time, you can access whatsappweb, [[https://web.whatsapp.com/]] i hope resolved your problem then mark solution, Thank you