引用自 norby89：

A trade is automatically closed when all the items on one side are greyed out. In order to reopen such a trade you need to "undelete" an item first.

Oh my god, I feel so stupid. Thanks a ton.

引用自 Blue Screen of Dea†h：

Maybe you are trying to open a trade with an item already listed in another active trade.

Nope, I only had one trade with the item in it.

引用自 LiSOmniDragon⑨：

https://steamhost.cn/steamcommunity_com/groups/tf2outpost/discussions/0/558747922562007365/#c540742485388491621

Read that and try the last steps, hope that helps.

I've tried every step, and nothing worked. I think it may be a feature to prevent people spamming.

引用自 LiSOmniDragon⑨：

Try refreshing the whole page. It may have something to do with what browser your using. I'm not entirely sure, I've never ran into that problem. Is the re-open arrow even on the page?

I've refreshed the page a ton of times. The arrow is simply non-existent.

I accidentally closed my trade a few hours ago, and, unlike all of my other trades, there's no option to re-open it. Is this normal?