Hi the experts,
 
We have raised a strange behavior with Windows Explorer running on Win7 or Win 10 station, trying to open/modify/save file located on Data ONTAP v9.1R12 filer (CIFS: SMB V1), here is the scenario:
 
- Put Windows Explorer on same folder than file test4.xlsx: K:root\Infra\Test\
- Open K:root\Infra\Test\test4.xlsx file with Microsoft Office Excel
- Make changes on file K:root\Infra\Test\test4.xlsx
- Save it <- OK
 
- Put Windows Explorer on upper level folder than folder of file test4.xlsx: K:root\Infra\
- Make changes on same file K:root\Infra\Test\test4.xlsx
- Save it <- Error (Document not registered error)
 
Important points:
- Error occurs only with xlsx and sometime with xls extensions
- Error occurs only with Microsoft Office (2010, 2013 and 2016)  and never with OpenOffice 
- Error never occurs with 7-Mode NAS whatever
 
Thanks for your futir advices !