4.6.12 upgrade failed, forums down

[pss999]

Help! For the first time ever, I've had an upgrade fail. After I logged into the upgrade system and started, it immediately showed a page saying "Safari can't open the page "https://www.concertina.net/forums/admin8600/?app=core&module=system&controller=upgrade". The error is "FetchEvent.respondWith received an error: ReferenceError: Can't find variable: reject" (WebKitServiceWorker:0)"

Now it's stuck. Even going back to the admin main page and trying again, the same thing comes up every time. And I don't see a way to stop the process, so my forums are now stuck offline.

Any ideas? I cleared the cache on the Support section of my admin, but that's all I can see to do. No other errors are showing.

Thanks,

Paul

[pss999]

Also, I just tried clicking on "Please also try disabling any third party customizations." and I get a page that says "2S119/1 The CSRF protection key did not match. This may indicate a plugin or theme is out of date. Please contact technical support for more information." which is weird because I'm running the default theme, no modifications or customizations, and I'm not running any plugins or apps or anything... my whole system is pretty bog-standard as far as I know!

[Nathan Explosion]

Use a different browser (Chrome)

[pss999]

Wow, that worked, thanks Nathan! Crazy, I never thought of trying that as this is the first time this has happened in MANY years! 

Thanks again, I really appreciate it.

Paul