Hi Varsha,
To drill down to the cause of the issue, you can try following this approach :
1. Top-level Folder > User security > Add the user as Principal & Assign Rights > Remove Inheritance > Full Control
2. Login to BI Launchpad and try to reproduce the issue
3. If error is reproduced, go to CMC and top-level Universes (if this is a universe based report) > User security > Add the user as Principal & Assign Rights > Remove Inheritance > Full Control
4. Login to BI Launchpad and try to reproduce the issue
5. If error is reproduced, go to CMC and top-level Connections (if this is a universe based report) > User security > Add the user as Principal & Assign Rights > Remove Inheritance > Full Control
6. Login to BI Launchpad and try to reproduce the issue
7. If this is BICS based report, top-level OLAP Connections (if this is a universe based report) > User security > Add the user as Principal & Assign Rights > Remove Inheritance > Full Control
8. If still not resolved, Applications > Webi > User Security > Add the user as Principal & Assign Rights > Remove Inheritance > Full Control
Regards,
Kunal