Exception in thread "main" org.apache.poi.openxml4j.exceptions.OpenXML4JRuntimeException: Rule M2.4 exception : this error should NEVER happen! If you can provide the triggering file, then please raise a bug at https://bz.apache.org/bugzilla/enter_bug.cgi?product=POI and attach the file that triggers it, thanks! at org.apache.poi.openxml4j.opc.internal.ContentTypeManager.getContentType(ContentTypeManager.java:340) at org.apache.poi.openxml4j.opc.internal.ContentTypeManager.removeContentType(ContentTypeManager.java:253) at org.apache.poi.openxml4j.opc.OPCPackage.removePart(OPCPackage.java:1016) at org.apache.poi.openxml4j.opc.PackagePart.getOutputStream(PackagePart.java:526) at org.apache.poi.xssf.usermodel.XSSFVMLDrawing.commit(XSSFVMLDrawing.java:204) at org.apache.poi.POIXMLDocumentPart.onSave(POIXMLDocumentPart.java:390) at org.apache.poi.POIXMLDocumentPart.onSave(POIXMLDocumentPart.java:395) at org.apache.poi.POIXMLDocumentPart.onSave(POIXMLDocumentPart.java:395) at org.apache.poi.POIXMLDocument.write(POIXMLDocument.java:221) at com.aqm.utils.ExcelCombine.combineExcel(ExcelCombine.java:169) at com.aqm.utils.ExcelCombine.main(ExcelCombine.java:52)