webERP 4.15 on hosted server sales order error

[swaminathan]

the version 4.15 seems to hide Sql error messages, does this needs to be enabled?
I figured this by installing both Ver. 4.13 and 4.15 on the same server and connected to common database.
database upgraded to 4.15 but php scripts in version 4.13 are same.
now the error has shifted from sales order entry to pdf invoice printing. with ver. 4.13 I get relevant Sql error message.
the same is not true with ver. 4.15. It throws a blank page or only header and footer.
anticipating help to resolve this.
Thanks