Ensure the ScriptManager is the first control inside <form runat="server"> . Also, add:
| Component | Status | |-----------|--------| | | Partially compatible (manual steps required) | | .NET Framework 4.8 | Fully supported (the toolkit's last compatible runtime) | | .NET 6 / 7 / 8 | ❌ Not supported | | Design-time support | Broken (Toolbox icons missing, drag-and-drop unreliable) | | Runtime behavior | Works if manually registered | ajax control toolkit visual studio 2022
Unlike old versions (which required manual downloads from CodePlex), you now install ACT via . Ensure the ScriptManager is the first control inside