We get this call a lot in support during the first few days of the year.  If you get this message there is a simple resolution, and that is to create the new inventory calendar for the new year.  

Please log into the KB and search for KB 55208 - "How to set up the inventory calendar" or click this link (login required) https://support.na.sage.com/selfservice/viewdocument.do?noCount=true&externalId=55208&sliceId=1&cmd=displayKC&dialogID=7608&docType=kc&isLoadPublishedVer=&stateId=7611&docTypeID=DT_Article&ViewedDocsListHelper=com.kanisa.apps.common.BaseViewedDocsListHelperImpl

Happy New Year!

Jennifer Pitt