Bug overview description.
Attempting to direct-link upload from FA would occasionally cause upload page thumbnail to freeze with the "Not Found" error. It will then cause FA to return a "403 Forbidden" error when clicking Download of that specific post, but returns normal behavior(able to view) on other posts.

The post will then be locked out(returning 403 error) for an indefinite amount of time, even after refreshing FA or closing the erroneous upload page.

The bug will correct itself after some time, but can only be fixed by first clicking Download, waiting for it to finally load, and then direct-link it to the upload page. If the first step is skipped, the bug will reappear.

What part(s) of the site page(s) are affected?
https://e621.net/post/upload

What is the expected behavior?
Thumbnail loads image of submission

What actual behavior is given instead?
Permanent "Not Found" error

Time of incident (if applicable).
12/3/2017 (10:25 AM UTC)

Can you reproduce the bug every time?
No, occasionally pops up.

What steps did you take to replicate this bug?
Direct-link upload from FA

Errors or other messages returned (if any).
"403 Forbidden" error on d.facdn.net(source link).

I reached the FurAffinity Forums and read that the "403 Forbidden" error would not turn up on d.facdn.net unless you are IP-banned or attempting to hack their servers.

So I'm not sure if this is a client-side issue.

I'm using Chrome 56.0, no proxy, on Windows 10.

TheGreatWolfgang said:
I reached the FurAffinity Forums and read that the "403 Forbidden" error would not turn up on d.facdn.net unless you are IP-banned or attempting to hack their servers.

So I'm not sure if this is a client-side issue.

I'm using Chrome 56.0, no proxy, on Windows 10.

maybe they banned e6 because they're jelly of its success
fchan has already done this (if you mention e621 there or link to it, you get the deliberately vague error message "posting not allowed", i.e. "we're censoring any mention of e621 but we don't want to admit it")

edit: read your post again, strange that it happens only on some fa posts

Could this in chance be part of their redirect that won't display certain images unless logged into FA?

Idk, could be part of their recent Beta Update changes.

http://www.furaffinity.net/journal/8120541

TheGreatWolfgang said:
Idk, could be part of their recent Beta Update changes.

http://www.furaffinity.net/journal/8120541

They're actually updating the site? Wow, I wonder how much they'll end up changing.

JAKXXX3 said:
They're actually updating the site? Wow, I wonder how much they'll end up changing.

Thus far only things I have seen is layout, they still have all the issues and bugs in place even with the beta layout. I can still see .png files which in reality are really badly downscaled .jpg images for example.

I genuinely hope they are also making underlying changes when they are releasing that update, because only reason for everyone to use that site seems to be because everyone is using that site.

As for original issue, at least direct URL uploading is just feature to make things easier, so if it's single posts with this issue, just download the thing to local memory. Alternatively take a minute to look up the image on sites that do not jpg downscale content by default if artist is using those.

This happens to me as well, but don't worry, the image should still upload. It also happens when I upload from tumblr.