http://purl.org/tcl/home/man/tcl8.4/TclCmd/bgerror.htm is the official man page. [[fill in useful tricks and examples for using bgerror]] Does the documentation describe the calling convention? I didn't notice it. My experience is that the error-handler invokes it as something like bgerror [firstLineOf $::errorInfo] During development, one might rush a hack like proc bgerror message { puts stderr "An event-based script faulted with '$message'." } into use. --- [Ken]: I want to enquire what is the best method if i got a proc that runs every 20s like the follow code but i want to catch its errors if any of the proc that run afterwards run into errors? I heard using bgerror is not recommended, so what is the best method? proc a { } { [do something] after 1000 a } ---- [Tcl syntax help] [Arts and crafts of Tcl-tk programming] [Category Command]