Frequently Asked Questions
Frequently Asked Questions
Common problems with Windows Defender and M-Files
Posted by Rami Aalto (M-Files) on 02 November 2018 12:46 PM

Windows 10 ships with it's own built-in antivirus software, Windows Defender. This is a good feature to have in any operating system. However, if another antivirus software is installed on the computer, Windows Defender should be disabled automatically. This isn't always the case.

We have seen several incidents where Windows Defender continues to scan opened files and ongoing processes even though there is already another antivirus software doing the same. This has lead to numerous different error situations, like:

  • Multiple "File downloaded" events M-Files Admin event log
  • Excel program opening when previewing an Excel document in M-Files (and the preview doesn't work if Excel is not open)
  • "Violation of PRIMARY KEY constraint 'PK_DATAFILEVERSION_BYTES'. Cannot insert duplicate key in object 'dbo.DATAFILEVERSION_BYTES'. The duplicate key value is (9810, 1, 0, 1). (ERROR: 2627, SQLSTATE: 23000)" error in M-Files client computer event log
  • General slowness of M-Files usage

As M-Files shows up on the client computer as a regular drive, the antivirus software also tries to scan it for harmful content. But M-Files works differently from a normal drive and antivirus software's realtime scans can cause a multitude of problems. That is why we recommend excluding M-Files from realtime antivirus scans, regardless of the antivirus software used:

In some cases this isn't enough and Windows Defender still interferes with using M-Files. In those cases it is worth trying to disable Windows Defender. More background information and instructions on how to disable Windows Defender can be found e.g. here:


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