"An error occurred inside the server which prevented it from fulfilling the request".

I am getting the following error message when searching my email: "An error occurred inside the server which prevented it from fulfilling the request".

It occurs with Chrome, Microsoft Edge and Firefox (even in an incognito/private browser window with no extensions). I am able to receive email normally but I cannot send email or search existing messages. This is an incredibly frustrating error and I understand it has been raised repeatedly with Xfinity before but continues to occur.