please check the following points:
* Make sure a VDP instance is up and running and that the VDP and web container port (9090 and 9999) are reachable from DMR network.
* Try using the VDP JDBC driver of you VDP server for denodo monitor. Put the denodo-vdp-jdbcdriver.jar in $DENODO_MONITOR_REPORTS_HOME/lib/ext/.
* If `denodo_monitor` database is not already present in VDP please check the option `Create Database in VDP` during DMR Surver configuration.
* Make sure the VDP user you're configuring in DMR is admin user or a user with administraion privileges over the server. Non admin user can only access the reports, but not configure the application
* If all the above steps did not solve te issue: stop DMR, reset by deleting the folder DerbyDB (in Windows, not deployed in a Web Container, it is located under C:\), restart DMR and try again the configuration procedure.
Link to DMR user guide: [Denodo Monitor Reports - User Manual](https://community.denodo.com/docs/html/document/denodoconnects/8.0/en/Denodo%20Monitor%20Reports%20-%20User%20Manual#h.bc13k226q4rj).
If you're still having the error and you have an active support account, you could open a support ticket and support team will assist you.
Hope this helps.