Cannot log in to website account

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 are 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) ..