Hi all,
I've updated FF to 78.0.2 but I continue to have the issue so I did some additional investigations
The problem seems related to the cache, with the firefox developer toolbar enable it worked because it had set the 'disable cache' option, if I turn off that settings it doesn't work, with a fast check of the http requests the problem seems related to an ajax POST to https://www.evernote.com/Login.action, with the cache disabled the request has the headers
{
"name": "Pragma",
"value": "no-cache"
},
{
"name": "Cache-Control",
"value": "no-cache"
}
and all works smoothly (response 200 OK), without those headers the response it's the error 418 (I don't ever know it exists ) so it seems a race condition that generates a bug on the evernote server