When Xeno shows a red dot instead of attaching, it usually means one of three things: the tool isn't running with admin rights, the launch order is wrong, or your build is outdated after a Roblox update[citation:1][citation:2].
Fix 1: Run as Administrator
A user on Microsoft Q&A reported that Xeno attached fine on their main account but showed a red dot on an alt account. The suggested fix was to right-click the Xeno executable and select Run as administrator, because the tool wasn't getting the same permissions[citation:1].
Fix 2: Correct Launch Order
Always open Roblox first, join a game, and wait until you're fully loaded in. Only then launch Xeno and click Attach. Launching Xeno before Roblox is ready is a common cause of attach failures[citation:2].
Fix 3: Update After a Roblox Patch
If Roblox pushed an update, old Xeno builds often can't inject until they're updated. Download the newest build using the button above, fully close Roblox and Xeno, then try again[citation:2].
Still stuck? Make sure the Visual C++ Redistributable and .NET Desktop Runtime are installed. If attach works but scripts fail, see How to Fix Xeno Errors.