Assume that you have a Microsoft SQL Server 2012 Reporting Services (SSRS 2012) or an SSRS 2014 report that has a tablix that will return an empty dataset, and you set the "NoHeader" attribute in the RsReportServer.config file for CSV rendering. In this situation, when you export the report to CSV format, the .csv file contains field separators.
Note The expected behavior is that the CSV output is blank as it was in the earlier versions of SSRS.
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Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.