Dashboard error Request processing failed. (XLS 000009) while trying to invoke the method java.lang.Object.getClass() of a null object loaded from local variable 'io'

SAP Dashboards 4.1 SP6

For some users, one of the query is fails and gives the following error when opening an uploaded dashboard from BI launchpad.The same query displays results for most users with no issues. Why does this work for some users and not others within the same group of users.

Any help appreciated.

Thanks

Ram