Error "Uh-oh, it looks like we have our wires crossed. Please try again later." - Not able to login.

Same here, really annoying. It’s been like that for days.

Still not working.

Finally was able to login after talking to support...

not sure if this will work for you guys but for some reason i am no longer able to log in from the main tmobile website. https://www.t-mobile.com/.    

From what i was told was because i’m a PREPAID  costumer the link between systems is no longer working and i need to log in through the pre-paid site. https://prepaid.t-mobile.com/home

This worked.

I was having trouble creating an account as a new user. I tried support both in chat and on the phone, both told me bullshit about “oh it’s being resolved, try tomorrow”. Unsurprisingly, it did not work “tomorrow”.

I used this link I found from a Reddit thread which took me to a different signup page that didn’t have the error: https://t-mo.co/2tdCnci

Thanks!!n this worked for me. I am prepaid.

Tried the app which wasn't ready for me, which sent me to the main tmobile site and I've been trying to login over there. But followed this direction and was able to get in.

I have a prepaid tariff and in the last 2 months I could not enter my account.  Only through this link you can go

https://prepaid.t-mobile.com/home

Being a postpaid customer, I got the same error on Firefox and tried using chrome (without incognito mode )and it worked.

I assume that somehow something is within Firefox temp. cache which prevented the site to open.