The report terminated with error: null

Hi ,

We are facing typical issue where the reports giving error like :

The report terminated with error:

null.

In the logs it doesnt showing any particular reason of error. instead it is showing only cache becomes invalid error

To Resolve this cache error we have kept cache size of 1024 MB and maxqueuesize kept 100 only.

Kindly do needful to reolve this error.

Detailed Logs :

[2019-06-27T12:12:06.936+05:30] [reports] [TRACE:16] [REP-50132] [oracle.reports.server] [tid: 29] [ecid: 6330ad10-1ddb-4e7e-9979-c20b81c8cbcb-00000002,0] [SRC_CLASS: oracle.reports.utility.RWLogger] [SRC_METHOD: writeln] checkForDbProxyConnection  Trying to get key from configuration file for db : dr