This article provides a solution for how to add section keys manually to a report. You might see this warning after trying to run "Fix report":
This report section keys are not possible to fix automatically. You must add unique keys in sections manually by using Visual Studio.
To remove the validation warnings, the placeholder LACRecId_DONOT_CHANGE must be added manually to fields in the report.
Lasernet plugin does not support automatic fixing for reports that are based on Query rather than on DataSource class.