我昨天遇到，steam support回復：
Are you attempting to make the purchase through Steam or with a web browser using the storefront webpage?
If using Steam, try the following:
If using a PC
-Exit Steam, then go to the location that Steam is installed to. By default this is C:\\Program Files\\Steam directory (this is the default with a Steam installation - if you set a different installation directory, you will need to browse to it).
-Delete all of the files except for:
Steam.exe
And the folder \\SteamApps\\
If using a Mac:
-Exit Steam and go to the folder Users/[username]/Library/Application Support/Steam
-Delete all of the files in this folder except for SteamApps.
Restart your computer and test the issue.
Note: This process will not affect your currently installed games.
If the issue still persists, try using a web browser (Internet Explorer 7 or higher, or Safari or Firefox if on a Mac) to make the purchase using http://store.steampowered.com/
If it still fails, try logging into your Steam account and making the purchase directly through the Store interface.
直接這樣貼沒違反版規吧？
※ 引述《taiwan540 (死阿宅)》之銘言：
: 不知道有沒有人跟我遇到一樣的問題~"~?
: 原本買的好好的
: 幫我自己跟朋友總共買了四個Payday2跟兩個DLC後
: 想再補買兩個DLC
: 從下午五六點就開始一直收到同樣的訊息了...
: "發生意外錯誤。購買未完成。請連絡 Steam 客服。"
: 什麼東西都買不了
: 網路上的各種解決方法幾乎都試過了
: 請問還有解嗎?
: 難道只能眼看著Payday2的優惠時間過嗎...!?