Error Attempting to Sell
Just click the sell button again in the mean time.
If you are getting an error attempting to sell, it’s likely an issue on your end. Restarting the game usually resolves it, but if you find yourself needing to do this repeatedly, you should contact support: https://en.support.guildwars2.com/app/ask/
There are several things that can cause the TP to burp and Support can help you troubleshoot them. There’s also some stickies in the technical support forum that address a few of these, e.g. admin rights (called UAC = user access control) and anti-malware software that interrupts the TP.
Good luck.
John Smith: “you should kill monsters, because killing monsters is awesome.”
I’m seeing it when selling several items in a short amount of time (clicking them and just giving them to the best bidder). Waiting 5 to 10 seconds usually helps. Seems like some anti-bot thingy.