Issue with Merger in initializing MergeDocument

We have a PDF file that is merged with dynamic data at run time using Dynamic PDF. We have been working with Dynamic PDF merger from quite some time and it was working fine but recently we are getting the below error that looks very strange.
This error is received intermittently.
Also there is no code changes done at our side.

Below is the stack trace:
java.lang.ClassCastException: com.cete.dynamicpdf.merger.wb cannot be cast to com.cete.dynamicpdf.merger.vb
        at com.cete.dynamicpdf.merger.ob.<init>(Unknown Source)
        at com.cete.dynamicpdf.merger.forms.PdfFormField.<init>(Unknown Source)
        at com.cete.dynamicpdf.merger.forms.PdfTextField.<init>(Unknown Source)
        at com.cete.dynamicpdf.merger.forms.PdfFormField.a(Unknown Source)
        at com.cete.dynamicpdf.merger.db.a(Unknown Source)
        at com.cete.dynamicpdf.merger.forms.PdfFormFieldList.a(Unknown Source)
        at com.cete.dynamicpdf.merger.forms.PdfFormFieldList.<init>(Unknown Source)
        at com.cete.dynamicpdf.merger.forms.PdfForm.<init>(Unknown Source)
        at com.cete.dynamicpdf.merger.PdfDocument.a(Unknown Source)
        at com.cete.dynamicpdf.merger.PdfDocument.g(Unknown Source)
        at com.cete.dynamicpdf.merger.PdfDocument.<init>(Unknown Source)
        at com.cete.dynamicpdf.merger.PdfDocument.<init>(Unknown Source)
        at qa.com.qib.omnichannel.integration.service.certificateOfDeposit.util.CODPdfUtil.createCODPdf(CODPdfUtil.java:79)
        at qa.com.qib.omnichannel.integration.service.certificateOfDeposit.util.CODPdfUtil.sendCODPdf(CODPdfUtil.java:46)
        at qa.com.qib.omnichannel.integration.service.certificateOfDeposit.route.SendCertDepositRoute.lambda$configure$0(SendCertDepositRoute.java:51)
        at org.apache.camel.processor.DelegateSyncProcessor.process(DelegateSyncProcessor.java:63)
        at org.apache.camel.management.InstrumentationProcessor.process(InstrumentationProcessor.java:72)
        at org.apache.camel.processor.RedeliveryErrorHandler.process(RedeliveryErrorHandler.java:398)
        at org.apache.camel.processor.CamelInternalProcessor.process(CamelInternalProcessor.java:191)
        at org.apache.camel.processor.Pipeline.process(Pipeline.java:118)
        at org.apache.camel.processor.Pipeline.process(Pipeline.java:80)
        at org.apache.camel.processor.CamelInternalProcessor.process(CamelInternalProcessor.java:191)
        at org.apache.camel.util.AsyncProcessorHelper.process(AsyncProcessorHelper.java:105)
        at org.apache.camel.processor.DelegateAsyncProcessor.process(DelegateAsyncProcessor.java:87)
        at org.apache.camel.component.restlet.RestletConsumer$1.handle(RestletConsumer.java:55)
        at org.apache.camel.component.restlet.MethodBasedRouter.handle(MethodBasedRouter.java:54)
        at org.restlet.routing.Filter.doHandle(Filter.java:150)
        at org.restlet.routing.Filter.handle(Filter.java:197)
        at org.restlet.routing.Router.doHandle(Router.java:422)
        at org.restlet.routing.Router.handle(Router.java:639)
        at org.restlet.routing.Filter.doHandle(Filter.java:150)
        at org.restlet.routing.Filter.handle(Filter.java:197)
        at org.restlet.routing.Router.doHandle(Router.java:422)
        at org.restlet.routing.Router.handle(Router.java:639)
        at org.restlet.routing.Filter.doHandle(Filter.java:150)
        at org.restlet.engine.application.StatusFilter.doHandle(StatusFilter.java:140)
        at org.restlet.routing.Filter.handle(Filter.java:197)
        at org.restlet.routing.Filter.doHandle(Filter.java:150)
        at org.restlet.routing.Filter.handle(Filter.java:197)
        at org.restlet.engine.CompositeHelper.handle(CompositeHelper.java:202)
        at org.restlet.Component.handle(Component.java:408)
        at com.backbase.portal.integration.shared.restlet.RestletRouterProcessor.handleRequest(RestletRouterProcessor.java:52)
        at com.backbase.portal.integration.shared.restlet.RestletRouterProcessor.process(RestletRouterProcessor.java:33)
        at org.apache.camel.processor.DelegateSyncProcessor.process(DelegateSyncProcessor.java:63)
        at org.apache.camel.management.InstrumentationProcessor.process(InstrumentationProcessor.java:72)
        at org.apache.camel.processor.RedeliveryErrorHandler.process(RedeliveryErrorHandler.java:398)
        at org.apache.camel.processor.CamelInternalProcessor.process(CamelInternalProcessor.java:191)
        at org.apache.camel.processor.CamelInternalProcessor.process(CamelInternalProcessor.java:191)
       at org.apache.camel.component.direct.DirectProducer.process(DirectProducer.java:51)
        at org.apache.camel.processor.SendProcessor.process(SendProcessor.java:113)
        at org.apache.camel.management.InstrumentationProcessor.process(InstrumentationProcessor.java:72)

Hello,

It is suggested to use latest version 8 DynamicPDF Merger for Java product jar file in your application and see if it works for you. You can download latest product files by logging into our CustomerArea using your version 8 DynamicPDF product serial number. Once you download the product files, remove reference for the older jar file and reference the latest jar file in your application.

If you continue getting any issues then please send over the following  information to support@dynamicpdf.com  so we can look into further.

1.        Input/source PDF using which you are getting error.
2.        Code sample which uses static data to recreate the error.
3.        Exact version and build number of the DynamicPDF jar file.
4.        Full error message along with stack trace.

Thanks,
ceTe Software Support Team