My OS is Windows 7. The page I found the bug on is: https://subeta.net/quests.php/saggitarius/finish I think.

I was doing Saggi's Quests and I was on quest number 10. I bought all the items the quest asked me to buy, and when I pressed the "Finish Quest" button, it said Error, that I don't have all the items that the quest is asking. And I did buy all of them. I checked in my inventory if I had the items and they were not there, like I didn't buy them. So I bought one of the items the quest asked me and checked my inventory and it was there (unfortunately I bought the most expensive lol). So I messed up and pressed the "Quit Quest" button. I just don't know what happened. I don't know if this just happened to me, or if it happened to others too. I hope it's fixed soon anyway. Thanks in advance!

Here is a screen shot:

Did you check if your sp went up?

sometimes you might have double clicked or the site might have "finished" the quest but just not processed it yet and so it shows you the error if that makes sense. Someone can probably give a better explanation.

I think I lost sP, cause I bought the item twice, so I think I didn't get my reward o:

Not with Saggitarius. Happened today with the Wizard Quests. I got a Quest Buff and I completed the 11th quest at the same time that the buff expired. I got my rewards this time :) (It said 11/10 quests completed)

I think so too. Thank you for the help :D