XHTML to Docx

Hi Professionals,

We are trying to use 'Xhtml to Docx' smart service(plug in) but its not creating the document. When we initiate(start debug) the process model ,it does not start,but in "Process Instances" tab we can see this process as active, and then it does not show any error or issue as well. When we tried to find this in System Logs we found the below issue, and  we do not have any idea what this issue means. Any help here would be appreciated. Thanks

Exception in thread "ThreadPoolTaskExecutor-173716" java.lang.NoClassDefFoundError: org/apache/commons/codec/binary/Base64
	at org.docx4j.convert.in.xhtml.XHTMLImageHandlerDefault.addImage(XHTMLImageHandlerDefault.java:87)
	at org.docx4j.convert.in.xhtml.XHTMLImporterImpl.addImage(XHTMLImporterImpl.java:1789)
	at org.docx4j.convert.in.xhtml.XHTMLImporterImpl.traverseBlockBox(XHTMLImporterImpl.java:1331)
	at org.docx4j.convert.in.xhtml.XHTMLImporterImpl.traverse(XHTMLImporterImpl.java:915)
	at org.docx4j.convert.in.xhtml.XHTMLImporterImpl.traverseBlockBox(XHTMLImporterImpl.java:1397)
	at org.docx4j.convert.in.xhtml.XHTMLImporterImpl.traverse(XHTMLImporterImpl.java:915)
	at org.docx4j.convert.in.xhtml.XHTMLImporterImpl.traverseBlockBox(XHTMLImporterImpl.java:1377)
	at org.docx4j.convert.in.xhtml.XHTMLImporterImpl.traverse(XHTMLImporterImpl.java:915)
	at org.docx4j.convert.in.xhtml.XHTMLImporterImpl.traverseBlockBox(XHTMLImporterImpl.java:1377)
	at org.docx4j.convert.in.xhtml.XHTMLImporterImpl.traverse(XHTMLImporterImpl.java:915)
	at org.docx4j.convert.in.xhtml.XHTMLImporterImpl.traverse(XHTMLImporterImpl.java:906)
	at org.docx4j.convert.in.xhtml.XHTMLImporterImpl.convert(XHTMLImporterImpl.java:555)
	at com.appiancorp.ps.xmlfo.ss.DocxFromXhtmlWithStyling.runSmartService(DocxFromXhtmlWithStyling.java:70)