While testing another modified SSRS report I noticed that certain values were not shown, only the message:
Checked the ReportServerService__*.log and ExecutionLog* database views, but they contained no clues about the error.
Then I used procdump to log exception messages from ReportingServicesService.exe with:
procdump.exe -f "" -l -e 1 ReportingServicesService.exe
Part of the result was:
[13:15:59] Exception: E0434F4D.System.FormatException ("Input string was not in a correct format.") [13:15:59] Exception: E0434F4D.System.FormatException ("Input string was not in a correct format.") [13:15:59] Exception: E0434F4D.System.InvalidCastException ("Conversion from string " norm" to type 'Decimal' is not valid.")
I extracted and ran the dataset query in SQL Server Management Studio.
Then looked for “norm” strings and found them in a column normally used to store numbers.
Attempts to convert these caused the problem.
My solution was to exclude them from the dataset query by adding:
AND ISNUMERIC(ValueString) = 1