You have error on any step of any task in NWA Configuration Wizard SAP Netweaver.
When You later tried to reexecute this step browser session had timed out.
When You look into the NWA configuration wizard overview your task is in status “Currently executing”.
You can restart Java Application tc~lm~ctc~cul~startup_app in NWA to resolve this.
After doing that the status changes to “Cancelled”, and you can execute your task again.