The reporting module has had a few problems that have repeatedly appeared in the Novib EVO App-Shell environment and elsewhere.
We are always striving to update the software to prevent such problems from recurring, but when no developer is available to provide updates, the following things can help:
Exception logs
When the application displays the message that "an error occurred on the server" without specifying detail of the problem, a developer can see more information about the exception in the exception logs.
The exception logs can be found on the /exceptions page of the backend of the system in question.
Sometimes the information the developer can glean from the logs is sufficient to solve the problem without software updates and without requiring much of the developer's time.
Datareader Logins
When data has been migrated incorrectly from one database to another, it is possible that a data reader login is referenced in the data that does not exist in the database that was migrated to.
To make sure that all report queries and report lookups reference existing data reader logins, edit them in the reporting UI and make sure that the Data Reader Login property is set to an existing value (i.e. any value you can choose through the UI).
Report Queries can be found on the Queries tab of the Datasource Details page. Report Lookups can be found on the Parameters tab of the Datasource Details page, by editing any parameter with the Lookup or Multilookup type.
Re-create data
It is generally a good idea to re-create any data involved in the report, when exceptions occur. This often solves the problem by re-initializing the values referenced by the report.
This can be done in a step-by-step way, starting with the most basic un-parameterized query that can provide data for a datagrid-based report and then adding parameters and specialized layouts.