When I go to wordpress.com, click login, I get the attached page. see screenshot Update: I now see that you're on mac running that version of Firefox.

Let me get on my mac running 10.13.6, I assume there should be no issues.

Somehow I got onto the login page once and the input box wouldn't activate, I couldn't type into it.

Did you already try Firefox in Safe Mode? I have no issues on my mac. see screenshot Let me install your version and see what happens.

It is possible that the server has stopped supporting your Firefox 78.15.0 version. Your can check the Web Console for possible error messages.

• https://firefox-source-docs.mozilla.org/devtools-user/web_console/

I've tried safe mode, no change, this is what I get in Web Console:

Uncaught SyntaxError: expected expression, got '=' entry-login.9fb7f62e4c1ec2634921.min.js:1:107264

STOP! log-in:31:17

Uncaught TypeError: window.AppBoot is not a function

   <anonymous> https://wordpress.com/log-in?redirect_to=https://wordpress.com/:28

log-in:28:8

Wait! This browser feature runs code that can alter your website or its security, and is intended for developers. If you've been told to copy and paste something here to enable a feature, someone may be trying to compromise your account. Please make sure you understand the code and trust the source before adding anything here. log-in:32:17 Failed to register/update a ServiceWorker for scope ‘https://wordpress.com/’: Storage access is restricted in this context due to user settings or private browsing mode. log-in:44:33 Uncaught (in promise) DOMException: The operation is insecure. log-in:44

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I get the same messages with 78.15.0 like you posted and this is quite likely a problem with this Firefox version no longer being supported. A possible solution can possible be to install a Linux distribution that runs on your current hardware to be able to run a more recent Firefox version. I do not have intermittent Firefox versions installed to test when it starts breaking, but 91 ESR works.

Dang. I was afraid this day was coming... thanks for taking the time to look into this, I really appreciate it.

Yes, it has come. Mark it as resolved and we welcome you.  ;-)