[ISC.0088.9321W] MTOM Attachments Processing Failed

[ISC.0088.9321W] MTOM Attachments Processing Failed: Cannot convert SOAP Message to XOP Package; base64Binary encoded data is not in the Canonical Lexical form.

Getting the above error in our server logs. Understood that there is an issue with conversion. Not sure where exactly we are facing issue & how to fix it. Could someone help me on this.

Are you the provider of the webservice or consumer? If provider then, it might be coming while converting to XOP (pub.soap.utils:createXOPObject). If you are consumer, then pub.soap.utils:getXOPObjectContent.