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I am also facing the same problem. I think we should all take a snapshot of the error message, in case we need to raise a technical issue in future.

That's what I did.

Anyway, I hope it's a blessing in disguise!
 
Update on website:

"Online applications: After we receive your application, it may take up to 5 days for you to see it in your account. We are working to make this wait time shorter. If your application does not appear after 5 days, contact us and report a technical problem. This issue will not delay processing of your application."
 
Update on website:

"Online applications: After we receive your application, it may take up to 5 days for you to see it in your account. We are working to make this wait time shorter. If your application does not appear after 5 days, contact us and report a technical problem. This issue will not delay processing of your application."
That's been there for quite a while. I'm still getting the bad gateway message.
 
Update on website:

"Online applications: After we receive your application, it may take up to 5 days for you to see it in your account. We are working to make this wait time shorter. If your application does not appear after 5 days, contact us and report a technical problem. This issue will not delay processing of your application."
The update message has been there for weeks.