If you get a critical error after updating the launcher, please make sure Internet Explorer isn't set to offline mode. Please replace uncheck the box that reads "Work offline" in IE settings.
You may also install the patch update manually. For more information, you can go to this LINK.
Please submit us a ticket and attach "WOTLauncher.cfg", "WOTLauncher.log", and "WOTLauncher.log.bak" to support if the issue couldn't be solve. You might find those files in the root folder of the game.