I have my own exception based on some condition and want to raise an alert when control comes in this catch block
catch (ApplicationException ex) { //want t
It's a bit hard to give a definitive answer without a bit more information, but one usual way is to register a startup script:
try { ... } catch(ApplicationException ex){ Page.ClientScript.RegisterStartupScript(this.GetType(),"ErrorAlert","alert('Some text here - maybe ex.Message');",true); }