WordPress login Not Acceptable

Try downloading WordPress again and delete then replace your copies of everything except the wp-config.php file and the /wp-content/ directory with fresh copies from the download. This will effectively replace all of your core files without damaging your content and settings. Some uploaders tend to be unreliable when overwriting files, so don’t forget to delete the original files before replacing them.

I did actually have downloaded the whole content with wp-config and all others files and uploaded into another server as backup so let’s say the server for backup is called b-backup and a-production is where I am having problem.

In a-production. I created a new folder to store ALL wp files in it as a backup. Then I downloaded the backup I have from b-backup onto my desktop and then upload it to a-production. Same thing still happens though. Also the backup I made into b-backup was a few days ago, and in my b-backup server I tried running the site and wp-admin the backup there and works fine that I can login.
In a-production the site works. Let’s say https://www.example.com would load and https://www.example.com/wp-admin would load too but if I click on log in. BOOM the error happens

Ok, so how about files from a fresh download, as mentioned above?

I will try that tonight….omg….but somehow if I use my phone and co-worker’s phone and I can totally login….honestly @_@ now

Have you tried disabling all of your browser add-ons or extensions?

not sure how to disable it once and for all but I just tried with chrome which only has one extensions. disable it and still the same. I am just hoping in few minutes when I am off work and try it back home that my desktop at home works. If it does, what I have in mind is somehow the gateway in office is blocking the transmitting if that’s possible. My phone is using data so it doesn’t have to do with the networking at office and of course both me and my co-worker uses the same network.

If it does, what I have in mind is somehow the gateway in office is blocking the transmitting if that’s possible.

Yep, either that or a security system on your host’s (or blog’s) end is block your office network. ??

totally weird…I just tried at home and both browsers are good.

but what’s funny is I think I mentioned the site works perfectly, even with the Chrome that was logged in I could still save and edit anything but firefox wasn’t working and once I logged out Chrome and trying to log back in chrome has the same error too which means the network just wouldn’t pass that page but there’s nothing special ><” just regular wp-admin page…

Hm, so are you running any security plugins? If so, one may have blocked your work IP. If not, I’d recommend checking with your hosting provider for similar.