Still getting F451 Error on Browser & Phone App

I've been having the same issue. I haven't been able to log in to my account for over a week. I've seen in some forums that this has been a recurring problem for over a year. And it's allegedly because T-Mobile is using third-party vendors (who buy our information from them) and that our browsers are rejecting verification sent from them. I've been on hold for an hour trying to speak to someone at T-Mobile. VERY ANNOYING. Ready to go back to Verizon.

I've been having the same issue as well. I have not been able to log into my account for the past four days. I've tried the chat feature and they told me to clear my browser history, which did not work. I cannot get a hold of any live representative of T-Mobile, including the number given to me by the chat person: 1-877-515-8640. I'm needing to access my account for work purposes, but to no avail...

Just made an account after googling the customer rep number given to me by chat. Our account is from sprint and since the transfer, it's been nothing but headaches. 

I was able to log into my tmobile account before and a week ago. I wanted to log in a few days ago to check my bill. As i logged in, it said my account security was low. To add either mobile auth or a phone SMS.

 I decided to put SMS and now any time logging in username + Pw and then prompting for SMS text, i get the same error. different phones, browsers, adblock, no adblock doesn't matter.  Chat has been useless, saying they would transfer me but never do. Say to call number but also useless. Might have to just leave all together and take our phones else where. Seems the account will be disabled since we can't pay. 

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F451 : Uh-oh, it looks like we have our wires crossed.

I’d found a workaround to this problem, which seemed to work just fine for about 2 or 3 months; but when I tried logging into my account a couple of days ago, I discovered that it was no longer working -- yikes!

I use the Brave browser -- and without getting into everything I tried in an attempt to resolve the dreaded Error F451, I'll just cut right to the chase. I finally reached a practical solution this very morning.

I found that with Brave’s 'Block fingerprinting' setting disabled, I am now able to exitosamente reach the T-Mobile login page. Moreover, I found that this will work even if trackers, ads, and cookies are not blocked within the browser. Here’s the steps for Brave browser:

From the 'Customize & control Brave' menu [the so-called hamburger menu in the upper right corner]:

   select 'Configuración' ➤ 'Shields'

   At the 'Block fingerprinting' setting near the bottom of the Shields page, click on the ▼ arrow and select 'Desactivado'  (the default setting is 'Estándar')

Once this is accomplished, you should be able to reach the T-Mobile login page. After logging off the site, I chose to reset Block fingerprinting back to its default.

I presume there’s a similar setting for other browsers; so hopefully this will finally provide a solution for all who have been experiencing this ridiculous error (which from what I’ve been able to find out -- ultimately fue caused by T-Mobile) .. 

If you have any anti-tracking software on, you'll get this message as well. Took me hours to figure it out. So now, I have to open my antivirus, turn off the tracking option, then I can log into the site. I use Avast which has Tracking prevention.

If anyone is having trouble making payments. There is an app called Ding top up. Use that to get a balance enough for the payment on your account that worked for me. It works for any phone number in the world. Hope this helps in any way.