I have an established Jaspersoft Studio 5.6.0 installation running on a Windows 10 platform and successfully connecting with an MS SQL 2008 database server. I have installed Studio 5.6.1 in parallel and have encountered a problem in 5.6.1 with the SQL connection. At first I observed an error with testing the data adaptor configured with 5.6.0. I searched these forums and found a thread that suggested adding an MS SQL Server JDBC JAR file to the Studio library. I found and installed the sqljdbc4.jar and the data adapter now tests correctly. However, reports that worked under Studio 5.6.0 now display an error similar or identical to the original data adapter error. Here's the error: net.sf.jasperreports.engine.JRException: net.sf.jasperreports.engine.JRRuntimeException: java.lang.ClassNotFoundException: com.microsoft.sqlserver.jdbc.SQLServerDriver at com.jaspersoft.studio.editor.preview.view.control.ReportControler.fillReport(ReportControler.java:468) at com.jaspersoft.studio.editor.preview.view.control.ReportControler.access$18(ReportControler.java:443) at com.jaspersoft.studio.editor.preview.view.control.ReportControler$4.run(ReportControler.java:335) at org.eclipse.core.internal.jobs.Worker.run(Worker.java:54) Caused by: net.sf.jasperreports.engine.JRRuntimeException: java.lang.ClassNotFoundException: com.microsoft.sqlserver.jdbc.SQLServerDriver at net.sf.jasperreports.data.jdbc.JdbcDataAdapterService.getConnection(JdbcDataAdapterService.java:173) at net.sf.jasperreports.data.jdbc.JdbcDataAdapterService.contributeParameters(JdbcDataAdapterService.java:128) at net.sf.jasperreports.engine.fill.JRFillDataset.contributeParameters(JRFillDataset.java:1019) at net.sf.jasperreports.engine.fill.JRFillDataset.setParameterValues(JRFillDataset.java:629) at net.sf.jasperreports.engine.fill.JRBaseFiller.setParameters(JRBaseFiller.java:1313) at net.sf.jasperreports.engine.fill.JRBaseFiller.fill(JRBaseFiller.java:931) at net.sf.jasperreports.engine.fill.BaseFillHandle$ReportFiller.run(BaseFillHandle.java:120) at java.lang.Thread.run(Unknown Source) Caused by: java.lang.ClassNotFoundException: com.microsoft.sqlserver.jdbc.SQLServerDriver at org.eclipse.osgi.internal.loader.BundleLoader.findClassInternal(BundleLoader.java:501) at org.eclipse.osgi.internal.loader.BundleLoader.findClass(BundleLoader.java:421) at org.eclipse.osgi.internal.loader.BundleLoader.findClass(BundleLoader.java:412) at org.eclipse.osgi.internal.baseadaptor.DefaultClassLoader.loadClass(DefaultClassLoader.java:107) at java.lang.ClassLoader.loadClass(Unknown Source) at java.lang.Class.forName0(Native Method) at java.lang.Class.forName(Unknown Source) at net.sf.jasperreports.engine.util.JRClassLoader.loadClassForRealName(JRClassLoader.java:175) at net.sf.jasperreports.data.jdbc.JdbcDataAdapterService.getConnection(JdbcDataAdapterService.java:145) ... 7 more A contact within my organization has suggested that only one Studio variant may be run on one device, but I'm reluctant to remove 5.6.0 as it works well for me; the only reason to upgrade to 5.6.1 is for like-to-like diagnosis of report creation issues. Thanks in advance!