Issue:

You receive a security concern notification in Word 2016 when opening a document from a network location saying:

Microsoft Office has identified a potential security concern.
The selection contains fields that could be used to share information from other files on your computer with an external website. It is important that this file is from a trustworthy source.

What is happening:

In my case, Word was picking up some Links in the current documents that it was flagging as a security concern. The links where related to some embedded images in the document footer.

Observations:

– Opening the documents from the local PC worked correctly and didn’t bring up the error.
– This was only happening with Word Documents, Excel, PDF etc were ok
– Altering Trust Center and making everything as unsecure as possible didn’t resolve the issue.
– The issue was happening with .doc and .docx files from the network location

Resolution:

Breaking the links (via properties) resolved the problem but wasn’t feasible due to the amount of documents that was effected in my case.

This appears to be a problem with the following release of Microsoft Office 365:
16.0.10730.20088 (1808)

The only way I could resolve the error for me was to downgrade Office to the following version:
16.0.10325.20118

Steps to do this:

1) Open Command Prompt as an administrator
2) cd %programfiles%\Common Files\microsoft shared\ClickToRun
3) OfficeC2RClient.exe /update user updatetoversion=16.0.10325.20118

Running the “OfficeC2RClient.exe /update user updatetoversion=16.0.10325.20118” command will start the download of this version of office. This could take a little but of time depending on your internet connection.