I have managed to loose access to my Facebook account/Messenger by accidentally logging out all connected devices when doing something on the Messenger app (can't remember which action; possibly changing password).
I had at that point already deactivated my account, but continued to use Messenger. Problem is, I never connected my phone-number to my account, nor have I written down the backup-codes for 2FA or linked a third-party code generator.
The problem when trying to recover
However, when I now try to log in and get the prompt to enter 2FA code, I click the "Need another way to authenticate?" link and then "Other options" -> "Get More Help" which leads me to "Confirm your identity" where you're supposed to be able to upload gov-issued ID and email.
At step 1 "How can we reach you?" i enter my email and click send, and it fails 500 server error and the process stops there (see image below).
I have tried to get in touch with FB, but it seems to be impossible. Nor have any of the help-center articles worked; "report" account via friend, clear all browser cache, etc.
Are there any other ways to contact FB and get manual assitance with this, or are there known reasons for this error?