Assume that you have a large Microsoft SQL Server 2012 Reporting Services (SSRS 2012) or SSRS 2014 report that contains many expressions. When you upload the report to Reporting Services Report Manager, you may receive the following error message:
An unexpected error occurred while compiling expressions. Native compiler return value: '[BC30494] Line is too long.' (rsUnexpectedCompilerError).
To work around this issue, move sections of the report into a separate subreport so that each report uses less than 1000 text boxes.
CauseReports that contain many expressions can result in dynamically generated code lines with lengths that surpass the line length limitation enforced by the Visual Basic compiler.
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.