If you want to export contacts from OST to vCard without any errors. So use the most effective exporting tool compared to other conversion tools name is eSoftTools OST to PST converter software that always allow to export or convert contacts from OST file to vCard and other variety formats without any errors. It provides a bulk conversion option where users can easily convert bulk OST files in one click and one time without any difficulty. MS Outlook is not required in this tool for conversion and recovery of OST files. 

Get more:- Export contacts from OST to vCard