Firefox suddenly won't open website

dalchina said:

The site seems dead- unresponsive. I suppose they might get it up and running again....

Maybe they have since you posted that. Right now it opens for me in Edge, IE and Firefox 56.0.1

Yes great working again, it was the authenticity of the data message that could not be verified that made me think it was Firefox at fault as there was no way of telling.

Thanks everyone or as they say in Swedish "Det är jättebra tack !"

Lol can you speak or understand Swedish ?

That's all you need....

Arcadian said:

Yes great working again, it was the authenticity of the data message that could not be verified that made me think it was Firefox at fault as there was no way of telling.

Seems it's usually not Firefox that's at fault, often it is the website itself that's misconfigured. Other browsers may ignore such errors, but Firefox seems designed to be more cautious (which I find reassuring). Here's a report of when it happened to Outlook.com about four months ago.
https://support.mozilla.org/en-US/questions/1161923