Cannot login to main account - "An error has occurred" on launcher and website

My main account cannot log in neither to the game servers nor to the website account.swtor.com.

I always receive one of these two errors:

"A server error has occurred. Please follow the Help Center link below for more information."

"An error has occurred. Please try again later. Return to SWTOR.com."

I made an alternate account and it works perfectly fine on the same PC and same internet connection.

I have already tried the following:

Clearing all SWTOR folders and cache

Running launcher as administrator

Language switch trick (change language → save → restart → change back)

The problem exists only on my main account.

Account/Legacy name: Noctecursor

Please check my main account for any session/authentication issue or soft-lock.

Thank you.