When using a Crosstab you have the possibility to add additional Measures (next to rows and columns).
If, for any reason, the measure class was wrongly defined you are unable to change this without resulting in a stacktrace. However the change is correctly applied (Closing and Reopening the report removes the stacktrace)
This was discovered in version 3.7.1
net.sf.jasperreports.engine.design.JRValidationException:Â ReportÂ designÂ notÂ validÂ :Â Â Â Â Â Â 1.Â TheÂ classÂ ofÂ theÂ expressionÂ isÂ notÂ compatibleÂ withÂ theÂ classÂ ofÂ theÂ measureÂ INVPLUSPIPELINEmeasure. Â Â Â Â atÂ net.sf.jasperreports.engine.design.JRAbstractCompiler.verifyDesign(JRAbstractCompiler.java:258) Â Â Â Â atÂ net.sf.jasperreports.engine.design.JRAbstractCompiler.compileReport(JRAbstractCompiler.java:140)
For this issue 2 workarounds have already been discovered. In the end both result in no change in the jrxml itself.