Error while clicking on Document references

When you see error in KanBo 2.2 while clicking on Document's references:

DocumentReferences {"DocumentsSourceId":3989,"Url":"/Velolösung als Virtuelle Maschine installieren.docx"} KanBo Exception: Element `Document with url /....docx in source 3989` not found at KanBo.Core.GetData.DocumentReferences.Invoke() at KanBo.Web.KanBoHub.GetData(String auth, Int32 getDataID, String method, String options)

Please try to attach and detach this document form any card.