Hi
In B4J editor put "breakpoint" on some line for example line 39 in Main program (your web example)39 "Dim params As Map = req.ParameterMap", put mouse over
ParametarMap and wait that data show in floating window instead "error evaulating expression" and then release program with F10 (step out). With this procedure data
come in right shape and web page is refreshed with correct return data. Hope that I answer correctly on your question? If you can, try put some name in field with char from CP1250 and will see error occur , on my PC which use this code page it is easy to produce!
Regards