There is a try catch like syntax in classic asp. use an on error resume next. Please read more aout this at Try-Catch-End Try in VBScript. Then you can reset the error status to 0 just before the db connection initialization. You can even have a function to collect all the error messages and dispaly at the end.
dim error_string 'initiate the variable
function readAndSetErrors(msg) 'Custom error message function
if err <> 0 then
error_string = error_string & "<br/>" msg 'Add the custom error message if there is an error
end if
set err = 0 'rest the error
end function
On Error Resume Next
'Connection string
strConnection = "driver={oracle in instantclient_11_2};DataSource=XYZ;Uid=username;Pwd=password;"
Set objConn = Server.CreateObject("ADODB.Connection") ' create connection object
set err = 0 'Reset the err just in case
objConn.Open (strConnection ) ' open the connection
function readAndSetErrors("The database is currently unavailable at this time") 'execute the function
' more code and may be more function calls
Response.write(error_string)